tell how he tries to make love to alice and why does he do so?

Charlie wants to make love to Alice, but he can't because his "other self" won't allow him to.

"Why was he afraid to let me love Alice? She sat on the couch, looking at me, waiting to see what I would do. And what could I do? I wanted to take her in my arms and..."

Thus, he decides to pretend she is Fay because that will make it all right......

"It disgusted me at first, but suddenly I realized the only way to overcome this paralysis was to outwit him. If for some reason Charlie was afraid of Alice but not of Fay, then I would turn out the lights, and pretend I was making love to Fay. He would never know the difference. It was wrong-disgusting-but if it worked it would break Charlie's strangle hold in my emotions. I would know afterwards that I had loved Alice, and that this was the only way."