I want to say that from the other view, I see that your wife actually handled it quite well. She tried to think and didn't panic. Why I say this, because she tried to stay with you instead of rushing to the surface. If she didn't get your point that you were only signalling the DM, she might have thought that you left her, as many said, while she was low on air and in need of you. But she still thought clear that and decided to trust you by staying with you.
It's quite understandable if I signalled to someone that I'm low on air and need you, and you moved away from me (although it was an misunderstanding) I could easily give up hope and go to surface for my air supply. It might be true that after that incident she held on to you tightly to ensure you being there.
Other thing, you said that she grabbed you octopus. I guess, it's one other sign that she tried to handle it calmly. Grabbing primary can means one of the ways that all a OOA diver close to panic can think of, to go for the source that surely work, because you just breath from it.
Even when you said that both of you practiced that she should just grab your primary, I still don't see why she is considered panic when she go for octopus, which I thought would be more difficult as the reason stated above and usually the octopus is clipped to the BCD to make it streamline and need a bit of effort to take it out, which is something a panic diver doesn't prefer.
May I ask, why weren't you be the one who hold her?
You could do it with your other hand. It's very important to show 'the you thought as panic' diver that it's okay and you are there for her. She obviously decided that she needed you, and by holding her you could give her a good confidence that you wouldn't leave her. I instead, you forced her to let go of your hand. It's quite drastic but as I said, she calm enough to see your point.
So, imho, you should be grateful that she reacted the way she did instead of a lot of worse possiblities she might go for if she was panic.
I'm one of the wife/husband buddy. We started it together so maybe that is a good way because we were learning together and not become dependent because one is more experienced that the other.
But I remember I had one occasion that I still looked up to him,
one, because he is my buddy and we take care of each other, and two, he is my husband, we take care of each other.
It happened on my first night dive on AOW training. I felt uncomfortable to dive into dark water and it was murky on the day dive. Not usual murky, but if you have seen miso soup in Japanese cuisine, that's like that. So I requested for him to hold my hand during the dive and he did so, in that way, I felt secure and the dive went well. After that, I fell in love with night dive and he never need to hold my hand again.
There was few occasions when one of us was low on air and we decided to do the safety stop, but the DM was wondering to far away. So, instead of catching up with the DM first, we informed other divers nearby in the group or just do the safety stop and keeping our eye on the DM. The DM (good one) should do some checking once in a while and at that time we could signal to DM that we are going up because we are low (provide that viz allow).
Where we have more dives to our belt, we develop another way. Actually, we use what we see fit for different situations. Because we always dive together we have mastered the hand signal between us, and the one who is not low on air will swim to the DM while the buddy is waiting or following slowly on the same depth then we surfaced together. It's also a good thing to be able to inform DM as you don't want the DM to think that you are alright when you are not because previously you were alright when you disappeared without telling him.
I don't really think that it's a must for your wife to try to dive with someone as as you said that she is very independent, it's only on that particular incident she was dependent to you and I can see clearly why. So it's okay to keep diving together, but don't patronize and especially press the idea that you are a much better diver that her. If you do, let her find out herself and learn, if you don't, she won't follow the wrong footstep.
For the hand signal, it's not something difficult to pick up if you learn to communicate enough. Without ever agreeing to particular unusual signal, my husband can tell me that 'a tiny fish is hiding inside this coral has a very funny face, wait for it to come out and see for your self', so it's a matter of practice and use and how to understand each other. Of course, for important hand signal, it's very important to master, whoever you dive with.
