Following as I have doubts as well.
13 years together.
He initiates sex often, which I suppose is better than not, but I feel like he's 'scratching an itch' , doing it for release, rather than attraction.
He doesn't touch me nearly as much as he used to. He does get an erection though on the occasional time he does. If I take my top off, he will touch but it really feels like he is doing it because 'that's what you do' when breasts are in front of you.
He says I look nice if I wear a dress or something for an occasion. He used to compliment my body ie legs etc, but now the only thing he compliments is how my vagina feels 

A major sticking point is that he has only gave me oral sex once in the past say 4 years (and that time was when we hadn't seen each other in 8 weeks). He used to do it often. I definitely don't smell or anything like that but something must've put him off. He denies anything is wrong and maintains he does want to (whatever, I don't ask cause that would feel forced). He constantly asks for oral sex though.
Sex is very mechanical, and has dwindled to 2 positions only unless I ask for something different.
Confusing if it's lack of attraction, selfishness, or just too comfortable.