Feeling disconnected from partner suddenly

I have been with my partner for 5 years. Started in high school. Recently I have felt less attracted to him and find myself looking other places. I would never cheat on him and it makes me feel so bad that I don't get turned on by him as much anymore. I love him so much and I don't want to leave but it's hard to talk to him sometimes and I can't work out why all of a sudden I feel different.. Has anyone been through something similar??