Before we were together, my current partner and I used to have casual sex, and he once told me that I was not the best sexual partner he'd had. Now that we're together, I find this constantly plays on mind. Often halfway through sex I'll lose the drive and desire to continue because of it, and even outside of sexual scenarios, It crosses my mind most days, even without any real reason to and usually has quite a negative impact on my emotions. Between it, and some other jealousy/self consciousness issues, it's rare a day goes by without me ending up feeling like dirt for a fair portion of it. I've discussed how I feel with him a few times, and each time we talk it through, but it doesn't seem to make a difference. I'm also worried if I keep bringing it up I'll seem too needy and whiney, and it will cause turbulence. Does anyone have any hints on how to deal with anything like this?