Mine isn't so bad as a lot of other comments here, but here we go:

A lack of effort/enthusiasm is a big turn off. When im in the mood and she isn't, I'll go all out and spend an hour or two getting her in the mood by teasing, massaging, talking sexy to her, foreplay, or whatever I can. When she's in the mood and I'm not, she just says "wanna fuck" and expects me to drop everything and be enthusiastically ready to go right away. There's no buildup, tease, foreplay... I haven't gotten a hj/bj in ages and can count on one hand how many of each I've gotten in the last year. I go down on her multiple times a week, sometimes just for fun, so it's annoying that a lot isn't reciprocated.