Why can't I cum anymore?

blueeyedbeauty

I never used to have a problem. Every time my fiance and I had sex, I would always cum, bucket loads! Lol but for the last couple of months, for some reason, I haven't really been able to. I don't understand why.. of course it still feels just as amazing as it always has, I just can't seem to be able to cum. Has anyone else had this problem, or is it just me?