Bad sex= end of relationship?

So my boyfriend and I have been together for a year and a half, and we just recently took a break, it was only a week but it helped with how I was feeling. I was really questioning how I felt about him and our relationship. I have been going through some big changes in my life, I started at a new school, I've met some super awesome people at my school (beauty school) and constantly being surrounded by people a lot like yourself really opens your eyes to a lot of things. I go to school five days a week all day and so I barely have time to see my boyfriend anymore and I feel this big distance and disinterest for my bf. But I'm starting to feel odd about or relationship again, like I was before the break I feel like I'm falling out of love? Idk. Now about the bad sex....we haven't had good sex in a while. Like probably months. Before our break we would have sex maybe like once every two and a half weeks. I really wasn't feeling it and he could sense that. I never orgasm while we have sex and he doesn't really do too much to help that. I just turned 20 and he has told me that he could see us getting married one day and that scares me. He's the only person I've been with and I feel like I need to explore more. There's a guy at school who I have the HUGEST crush on and  I want to talk to him but I just feel guilty doing that even though I know that's not even remotely close to cheating. When my bf and I took our break he was ruined and so upset about it. He told me he didn't eat and couldn't get himself out of bed and I can't bare the thought of making him feel that horrible by actually ending the relationship. I've never been in this situation before because I've never had to break up with someone who I was/is maybe still in love with. I need advice. I know the guy at school is graduating in May and all I know about him is that he's a good singer and his name.