I have gone of sex and don't know why ?

Has anyone just got no desire for sex and went right off ity boyfriend constantly moans about it and that puts me off even more but I just feel like if I'm not in the mood and don't want to do it I'm not going to be pressured into it cos he wants it I do understand that his needs are important too but moaning and starting arguments just pushes me away. So I guess my question is has anyone felt like sex as more of a chore than something you enjoy?? And just feel like u could happily not have sex again??