High school sweethearts

Megan
So I've been with my high school sweetheart for nearly 6 years years, we started dating my freshman year and I'm in my third year of college. I love him very much and actually just moved in with him in an off campus apartment just for the school year. However, I can't help but feel that I missed out on dating other people like all my friends had done. I've been feeling this for a year and recently confessed my feelings to him and he said he fel the same way, but not as badly as me. I don't think I want to break up with him, our relationship and sex life have been sort of lackluster lately but in general I think I'm fairly happy with him. That being said I'm not sure if that is what the feelings are coming from or if I'm genuinely sad I missed out on dating. I really want to stay with him, but I don't think my feelings are going to go away anytime soon and I don't want to life the rest of my life like this. I guess my question is high school sweethearts, did you ever feel like this? What did you do about it to get through it?