For starters, make no mistake about it, Fixit15, or at least fixit16 (when he had a car) did pretty well for himself. rockin' bod, popular friends and many willing girls (BJs readily available- sex, no so much). The prospect of a girl getting naked, sleeping getting into the same bed and willingly offering sex would just be beyond his belief. Although, speaking of novelty, fixit16 had a SERIOUS problem with cheating on his girlfriends. In fact, Fixit's wife may be the first girl fixit did not cheat on...
So, maybe there's something to be said for novelty.
But overall, I think it's a complex question. I can try to give you the answer, but so much has changed recently that I'm not sure I know the answers to a lot of questions anymore.
My best guess has to to do with timing. I usually engaged in MB in the morning, sometimes during the day. Sex with W was exclusively a night time activity. And it had to occur before "it was too late to ask for sex" So I guess it was just easier and less trouble. I was too lazy to put the effort into it? sort of like I could cook myself a great dinner every night, but I usually just eat microwave food (which isn't as good) because it takes less effort to deal with.
I know ignorance is no excuse, but some of it may have had to do with me not realizing it was a problem. I didn't really start thinking about my relationship until after the bomb. Since then I’ve been VERY reflective. Probably too late, but I’ve learned a lot about myself and how to maintain a relationship (whether with my wife or with whoever comes next). It was just beyond my comprehension that my wife would threaten to leave me. I thought I was doing what I was supposed to be doing: earning a paycheck and manning the barbeque on the weekends. I have no idea why I didn’t think about how my wife was feeling. I was happy with the marriage, I guess I figured she was, too.
Again, I didn’t think about it much, but I guess I just figured sex was a hassle for her and it interfered with television time. Remember, we had to go to bed early (and forego some television) to have sex on time. Also, she wasn’t overtly begging for it, either. She has since identified subtle signals, but I didn’t pick up on them. Gauging against my close friends, MB and infrequent sex was normal.
There’s also the “it’s always available” mentality. An analogy: when I lived in NYC, I never went to the top of the WTC. It’s always available, no reason to take a special trip to go there. Maybe later if someone visits from out of town. Well, now it’s gone and I’ll never get to see the view from the top. Until it was attacked, however, it was nothing particularly special. I think sex with wife fell into the same category. Hmmm... why miss a re-run of CHiPs tonight when I can always have sex tomorrow night?
So, yes, it was because I was an ungrateful turd. I have no idea why, beyond that fact that I didn’t foresee the consequences of my actions. And I was lazy. I wish I knew all along what I know now...