I’d like to chime in here as the OP hit pretty close to what-used-to-be.
I was married for 7 years.
Best friends, no fights, joined at the hip. Just like you.
However, the sex with my wife was just “blah”. No more than once every other week. No foreplay (from her, at least), no oral (from her at least), and no intimacy (which is **much **more than sex). It was all bang-bang-bang, get it over with. More than a few nights I was promised intimacy (don’t read that as just sex – all I wanted was to be close to her), only to have her snoring on the couch by 7pm. No apologies the next day. In short, she was a very selfish lover.
I thought as you did that she was sexually abused/attempted rape or something somewhere in her life.
I bought her books, communicated rationally (from me at least), and gave her everything she wanted in and out of bed (as far as intimacy is concerned), but she flat out refused anything I would ask for. Or worse yet, agree to it, then never perform nor mention it again. All I was asking for was foreplay. Nothing unreasonable.
It killed me. For 7 years I convinced myself that I was a better man for not treating satisfying sex as importantly as communication and commitment.
I was wrong. A healthy relationship is like legs on a chair. Intimacy, commitment, communication and compromise. Without any of these, the relationship is doomed to either fail or be a miserable existence. Intimacy (not just sex) is included in this classic tripod because without, you’re just friends.
When I found myself rationalizing to myself that if an affair fell into my lap, I wouldn’t refuse, I knew the relationship was doomed.
It is not unreasonable to ask your SO to compromise to something that you feel is important in a relationship. That’s her role in the relationship As long as your requests are not unreasonable. That’s your role in the relationship.
I guarantee that if you go unfulfilled (sorry about the pun) in one area, it WILL bleed over into the others unconsciously.
If it bothers you this much now, ignoring the issue or following the same way of thinking I did will not make the situation any better. Do something about it before breaking up with her involves lawyers and child support payments.