Works fine on my end, so can you tell me exactly what's wrong when you reach that scene?
*SPOILER WARNING*
Click on both his nipples with each object. A small dialogue will appear in each option. Once you have passed these four pieces of dialogue, the regular arrow click will appear again and the game will proceed to the sex scene.
I've passed through this scene at least a hundred times while betatesting, so unless you've touched something in the code, it must work.