A brand new diver does not belong on a deep dive, a night dive or especially a deep night dive, regardless of what the DM said or did.
Hmm...this comment got me thinking. I thought I'd offer the perspective of a newer diver, FWIW. I did my first diving post certification + refresher on a live-aboard trip. My spouse/buddy was also a brand new diver and we dove with another novice couple and a DM who was a great instructor. We were the only group of new divers on the trip, and it became obvious that the operation had teamed us up with their best DM.
On our first day of diving (my first ever in the ocean--got certified in fresh water) we did a 2 dives and then a night dive. The night dive was at the same site as our second dive, so we had already dove the spot. Although we were all nervous, we had a great dive and I found it both exciting and peaceful. Seeing the changing ecology of the reef was so interesting and I'm glad I did it!
Did we not belong on that dive? I don't really know, but we were well briefed, did a fairly shallow dive (50' max and most of it around 30-35'), were in a very small group with the boat's most experienced DM, had redundant lights/glow sticks, etc. and everything went very smoothly. I'll admit I felt a little disoriented on ascent, but the mooring line and lights from the boat helped and everyone in our group raved about the dive afterward. I'll also freely admit that a little more experience would have been good in case anything did go wrong, but I'm also glad that I did the night dive right away because it demystified the night dive.
Was it a "trust me" dive. You bet. But being with a great DM also made it a very positive learning experience.
Since this time I've dove with both great and not-so-great DMs and have learned from many of them. Trust me dives are sometimes a fact of learning, and can work well if you have a good DM that is not in charge of a large group and has time to devote to you and to help you advance your skills. That said, my spouse and I have also learned that the DM doesn't always know best, and that, too, has been a valuable lesson. We've learned to learn from watching and talking to the DM, but we've also learned we must
rely on each other, rather than the DM.
Best of luck to you and your wife in your future diving, Divedeepr!