I see guys do this alot when the kids are little or someone is pregnant ..
I'll hold back though ..

Anyway

We all have responsibilities that we have to see through and this is one of them . What happened is ,instead of saying "landing" you , she allowed it because she was in love with you and did not want to lose you is more likely .. Alot of us including me have done this and its common plus she was very young also ( comparatively ). She was doing all that she could do at the time to try to accept it .. Then also we don't know what your dressing was like , if you took it too far which many do when they get a green light etc so there are alot of variables here that we really don't know .
There are alot of behaviors that come along with dressing that are the big turn offs . Way more than the dressing itself so you have to really look at your self and look back over your relationship too ... its rarely only one persons fault . Kids are stressful and she probably needs your help instead of worrying about this . Life really changes when kids are in the picture and no I do not think that dumping your family for dressing 24/7 is the right thing to do .. not saying that you think that but plenty here do .

I always hate it when someone disparages a female spouse here without hearing the other side but it is what it is.