How timely this topic is…
I just returned from a few dives in Roatan where I was buddied-up (by the dive outfit) with a VERY newly certified diver (he had received his OW the day before and didn’t even have a permanent number yet). During our ride out to the sites acknowledged that he wasn’t yet comfortable with his trim & buoyancy and during our first dive I could see why. He was task loading and more focused on his non-tethered GoPro that he kept dropping rather than continuing to get comfortable underwater and honing his skills & buoyancy. Several times he was knocking into the sponges and corals while trying to “get the shot” and stirring up the sediment in the process. I talked to him about what I observed during the surface interval, and he acknowledged all that I mentioned and suggested. Then came the second dive…
We were taken to another location on our second dive that had zero current but more valleys, semi-enclosed overhead formations, and overall varied reef structures. Our DM would check in with us regularly but allowed us all to explore and dive at our own pace - which I enjoyed since I was having a great time viewing the flora & fauna (and mighty proud of my buoyancy and trim control - lol!). At one point my buddy - who was nowhere near the DM - decided he was going to go through an unfamiliar swim through that was mostly obscured and angled at a downward descent towards an unknown exit point. He tried to get me to go, to which I signaled no and tried to tell him not to, then when I refused he dropped and started going through. I looked around for the DM to signal with my light that he needed to get over there and stop this, but with no success. I watched my buddy’s bubbles rise through the cracks as he made his way through the unknown and finally exited out over a reef wall about 40’ from where he entered. At this point, I was livid but the buddy was cheering and celebrating like he had just won a million dollars. A thousand what-ifs ran through my head while he was down there, and all I wanted to do after was let him know how irresponsible his actions were - and that in no way was he ready to do that again.
We finished the dive roughly 20 minutes later with his continued GoPro dropping and sediment stirring even as I was trying to get him to refocus and/or end the dive early. On surface I asked him how he thought he was ready for that and his reply was that he “just went for it”. Never was I so happy to be done with a buddy to-date. I have a feeling that at some point he’s going to be a statistic, though I don’t wish that on him or anyone with whom he dives.
My few observations - and I’m open to any feedback and/or suggestions on how to address this in the future:
1) incorrect pairing from the start. The dive outfit didn’t take the time to assess the individuals’ skill levels and pair accordingly - they just asked “does everyone have a buddy?” then paired us up from there. Had they checked I wonder if they would have paired differently (I still have a lower number of dives at 26, but have been diving conservatively since certified in multiple locations, and focused on buoyancy since the beginning)
2) unattentive DM with too large of a diver-to-DM ratio. We were 1:10 with all ranges of ages and levels - better planning and lower ratios might have helped this.
3) clear-cut expectations from the dive op and DM. Most places I’ve dived with have been very clear about the plan and what can/cannot be done by the divers. This was minimal at-best with this op - which was disappointing for several reasons, mainly because this is a PADI 5-star training Go Pro training center, and it was where I had a phenomenal first Discover Scuba experience which led me to certify.
My apologies for the length of the post, but felt it was appropriate and timely for the group…
Happy SAFE diving!
It would have been perfectly reasonable for you to ask the boat staff to find you a new buddy after the first dive. Concluding this brand new diver was exhibiting both poor skills AND poor judgment (by carrying a camera) would have been reasonable and - in my opinion - perfectly valid reasons to explain to said boat staff.
The advice to never let someone buddy you up with someone you don't know is absolutely terrible, in my opinion. You can't necessarily take your own buddy with you everywhere, and you're not ready for solo diving yet. So, whether you find your own insta-buddy or the boat staff does it for you, you need a buddy. The conversation you should have with that buddy is the same, either way. And if you determine that you are buddied with someone you are not comfortable diving with, then absolutely find a different buddy!
That your buddy left you on the second dive is really bad, regardless of why. Whether it was to do a swim-through or for some other reason, your buddy left you. On purpose.
All that said, your buddy's judgment is not your responsibility. Do not take it on yourself to feel like it is your obligation to educate them on why they are doing bad things. I mean, you can if you want to. But, in a situation like that, it is okay to simply tell yourself "I am not diving with this person anymore" and then proceed from there. If your buddy leaves you, consider whether it is simply time to end your dive and ascend, the same as if your buddy was lost by accident. Get back to the boat and report that your buddy swam into a hole in the reef and you don't know where he is now. That insta-buddy would have probably gotten a real eye-opening education if he had come out of the swim-through, not been able to find you, and then when he got back to the boat, found that the boat was conducting a lost diver procedure to find him...
You don't need to be the scuba police. Let the boat staff do that. If you ever have to end a dive early because of a bad buddy, chalk it up to experience and move on - with a different buddy.
To your points:
1) WAS it an incorrect pairing? What is an incorrect pairing? It will be rare to need an insta-buddy and find someone who has exactly the number of dives and training (and etc.) as you do. If one of you was on Nitrox and the other on air, and the dive deep enough for that to matter, then I would probably call it "incorrect". If it were a shallower dive and one of you had much bigger tanks than the other, or a much better SAC rate, then I would probably call it "incorrect".
A bad buddy is a bad buddy, whether they have 1 dive or 1000 dives.
It was probably actually a good thing (for him) the other guy was paired with you. If he was paired with another brand new diver, the other diver might have followed him into that swim-through. And then both feel encouraged to do another one, and so forth. Both ending up as statistics.
And the bottom line: You and only you are responsible for you. If you are buddied up with someone you don't want to dive with, it is on YOU and nobody else to fix the problem. You can ask for help - i.e. from boat staff. You can choose not to dive, if there is nobody to buddy with that you are comfortable diving with. But, faulting the boat staff for you having a bad buddy is not appropriate, in my book. I don't view it as their responsibility to provide you a buddy. They are doing you a favor by helping you to find one.
What if you end up on a boat where every other diver already has a buddy and nobody is willing to buddy with you? Is that the boat staff's problem, or your problem? Like I said, in my opinion, it is your problem because the boat staff is not obligated to find you a buddy. They are doing you a favor when they help you find one. Fortunately, I've never seen it happen that someone couldn't dive because nobody would buddy with them. Most divers are nice and happy to help others - especially a new-ish diver.
2) Unattentive DM? Again, you, and only you, are responsible for you. Having a dive pro in the water with you is a luxury. A lot of charters don't put one in unless you pay extra to have a DM as your buddy or guide. Expecting a DM to solve problems you are having with your buddy is inappropriate, in my opinion. Unless it's an actual emergency, of course.
If you have an OW card, then you are certified to dive unsupervised. If you do not feel comfortable diving without an experienced diver staying close by your side and solving problems for you then your OW instructor did you a disservice and you should consider getting some more training. Or at least pay for a guide to dive with you until you do feel comfortable.
If you don't feel comfortable diving with a train wreck of a buddy, then you should not show up expecting to get paired with a random person. Bring your own buddy or pay for a guide. An insta-buddy could ALWAYS turn out to be a train wreck, and if you go in with a plan to dive with an insta-buddy, then be prepared to lay in it, so to speak. Certainly don't blame the DM or the boat staff. If you want them to ENSURE you have a solid buddy, they will - and they'll expect you to pay for the guide they provide.
3) Dive ops with the least rules are generally my favorite. What expectations did you expect them to communicate which they did not? What things did you expect them to tell you that divers can or cannot do? What expectations did they have that you only learned about after the fact? What rules for "can or cannot" did you learn about after the fact? It sounds like the answers are none and none. In which case, they DID communicate everything they needed to...?
Putting you in the water and letting you do whatever dive YOU want to do sounds perfect, to me.
All in all, nothing that you reported comes across to me as a negative towards the boat staff. It comes across to me as you having expectations that were not met. And, to me, those expectations (of the boat staff) were not realistic nor reasonable.
I wish you had posted a link to where I said that. I always like reading what younger me said, to see if older me thinks younger me was right, or an idiot. LOL! 
