I don't do it for you anymore... HELP!

My boyfriend and I have been together for 9 months now, and the sex used to be amazing. But for the past month I've really struggled to orgasm and I feel like he's been struggling too. I feel like I don't do it for him anymore. I know my problem is just thinking too much and that's why I have a hard time reaching orgasm... I'm afraid to talk to him about it and I'm afraid we're going to break up bc of it. I love him so much and I don't want to lose him. Our relationship is pretty much perfect... except for the sex... which is kind of a big deal. Oh, he's 29 and I'm 24. I feel like I'm too young to be having these issues. I really want this relationship to work... I love him and am attracted to him! Idk why all of a sudden we're having issues. Idk what to do! HELP!!