What is wrong with me..

My SO and I have been together for 3 years now and just as recently I lost desire in sex, not that he isn't good enough or that the sex isn't good enough because when I am in the mood it is the best. for the first 2.5 years of our relationship we had sex 2 times a day sometimes even 3 and just as of 6ish months ago I started only wanting it 1 time a week if even that.. I've hurt him to his core I am an emotional wreck because I want it so bad but I'm just not craving it like I used to (not him, I still crave him). PLEASE HELP! Its putting a huge strain on our relationship.. Thank you..