I usually see your guy's point, but you are off base here. She sounds like a trauma survivor. People with traumatic childhoods act out their traumas in their romantic relationships more often than not. It's actually quite common for therapists to advise clients to try and date people who they don't find instantly attractive as a way to find a healthy relationship. Pia Mellody has some pretty good books abouts about the subject geared slightly more towards women (men can get some good insight too, though).

Yes, she should have told him upfront, especially if she is doing this on the advice of a therapist. Building relationships on honesty is one of the main steps in this type of thing. Also, his feelings of hurt are completely justified. I do think it's something they can work through. If she truly is with him because she is trying to be a better person, and he helps her do that, then I really don't see a problem. That's the entire point of relationships in the first place.

Disclaimer: I found this on r/all/top and I've been happily married for six years. Make of that what you will.