Pardon me for sounding like I know what I'm talking about (because my own MR is completely FUBAR) but ...
Thinking back on when I was in my early 20's ... and the women I knew back then ... it just make heckuvahlotof sense to me ... she got into a very serious relationship (marriage & child) early on, and, for whatever reasons, had very serious doubts ... and now she's trying to exorcise all those demons. Her behavior isn't going to make a lot of sense for a while. She's infatuated w/ the new guy but also tethered to the comfort you provide. I'm willing to bet you a bagel (toasted w/ cream cheese, and a venti macchiato w/ coconut milk on ice) that her fling w/ the OM isn't going to last. The question is whether when she's done thrashing, she's going to feel ready to jump back into a committed relationship -- that might be really tough for a 24-ish year old -- AND whether she's going to find you to be attractive as a long-term partner. Tough call.
The upside to your situation is that she's relatively young, so has fewer years' worth pent up demons to exorcise than a mid-40's woman who's put up with H leaving his dirty laundry in the wrong places, and passed up flirtatious male attention at social gatherings and bars and restaurants for years.
The downside is that at mid-20's ... a woman (or a man) is less likely to have a sense of what the hell s/he wants out of life, whether s/he is ready to enjoy the fruits of a stable, loving, long-term relationship.
Anyway, I hope you put the cake away. The trick -- which I have yet to get a good grip on -- is to detach clearly but w/o seeming to turn a cold shoulder. Be detached but make it clear the door is wide open to rebuild your marriage if/when she's ready. Don't give her another mouthful of cake though, til she drops the OM.
Me: 50, MLC/WW 45 Young kids Nov 2015: BD1 Apr 2016: BD2 Jan 2017: W filed Feb 2017: D final
