If you've been holding onto a LOT, it's possible to spend the entire length of the experience processing everything you've lived up to that point. I've seen it in first-time MDMA experiences, notably a friend in his late 20s who'd only recently 'come out of his shell' so to speak.

I think even in that case, his experience was probably wildly useful, despite bearing little to no resemblance to the happy empathic presentation that's commonly associated with MDMA.

My answer is 'yeah, probably.' But ideally this hypothetical couple should ask someone experienced who knows them better.

This is probably the opposite of what you're looking for, but semi-regular, um, psychedelic therapy kept me in a relationship that third parties call "abusive."

During the experiences we were in absolute perfect unity, learned lots about each other, and defaulted to kindness.

This carried over for a few weeks where the experience would be fresh in memory. I fell into the trap of "it is possible for her to be better, so she will get better because she loves me."

It can be an awesome experience om many drugs to share it as a couple. then again e.g mdma can be used for many things. Shulgin's (creator) wife used it a lot and said it was great for reading on.