Why is he so desperate for sex?

I haven't slept with him in months bc he is in a relationship. He still texts or call me but its for sex. He knows we can't sleep at his place so he wanted to come to mine or somewhere public. I rejected once. He tries to get me again but this time make exceptions, he pretends like he doesn't have a girlfriend, invites me back to his place which is still a no. I blocked him but he tries again from a different number asking me for sexual favors.

Why is he so desperate for sex?
Post Opinion