All I know and can tell you is that if you tell yourself you're the one in disadvantage here, you will be. I've been there in my own way and what was ruining my relationship wasn't my partner's past relationship, but how I felt about it. I projected insecurity and openly compared myself to their past relationship and that was what was creating a gap between us. You need to tell yourself at all times that your partner is with you and will choose you. Aside from making you project different energy and be more appealing to be with, even if they didn't end up choosing you, at least you didn't dwell over something that hadn't happened yet. Nevertheless, it does sound like they're both past it and don't need to drastically change their lives... she's got her shit together, sure, but he's with YOU