I do agree with Big Mama in that it may be broaching on problematic...it's not the sex itself being the issue, I don't think, but I am a concerned over your rationale. What I would suspect as a major underlying factor is your self esteem. A major signal of that to me was that you don't expect your partner to care about you, and that you find someone being generally nice to you to be strange You, in a sexual encounter, go in expecting nothing positive to come to yourself out of it and what seems like a sense of obligation to the other guy. That's not healthy to yourself Wend. You deserve better and owe yourself better.

I think seeing the school therapist would be a good idea. You don't have to mention any specific details that you don't feel 100% comfortable sharing, and there's no pressure. They're only there to help.

Going back to you, I think it's important for you to see the good in yourself. You deserve a guy who'll care for you for more than what you can do for them. What is it, speaking generally, is it about your life that makes you unhappy? Could you identify some things you could do to change that?

Speaking a little more bluntly, please don't feel obligated or that you owe sex to anyone. You don't, whatsoever. It's a kind gesture for him to help you with your car, but you don't owe yourself to him simply due to a kind gesture. You are, frankly speaking, worth more than a mere kind gesture.

Lastly, speaking to the SA, I wouldn't be surprised in the slightest if that influences your current day sexual behavior in at least some regard, as Big Mama suggested. I did want to extend this though: You should feel immensely proud of yourself for getting through it as you have. SA is one of the most heinous things one can inflict upon another. You being here and trying to improve yourself should speak volumes to yourself for your own inner strength and courage. If nothing else, be proud of yourself for the strength you've displayed. Things may not be perfect, but you're trying, which is sometimes the best we can do.

I would offer as well that anything I can do for you, I'm only a PM away. Please, know you're in my thoughts and prayers, and that I'm rooting for you.

Hugs,
Harley