Don’t want sex

I’ve been with my partner 2 years but lately have no sex drive. I don’t want it. It’s decreased more and more over the last 6 months. I’ve done it cos obviously I love him and he wants it. But I just don’t enjoy it anymore. I can’t get in the mood. And I just don’t want it. Does this mean I’m a bad girlfriend? Or in reality if I’m not wanting or enjoying sex should we not be together?

He will say ‘can we have sex tonight’ and at the time then I feel like yeah ok but then when it comes to that night I really don’t want it and I’m finding excuses like I have headache and I’m tired and I don’t feel too good.

Edit : I have given him a hand job and a blow job to try keep him happy. But it’s more about me actually not wanting sex or him to pleasure me