When I finger my girlfriend I never know if she comes or not.

It’s sometimes hard to tell whether a girl has come or not, their responses differing greatly at the moment of orgasm. Some start to shake and have involuntary spasms, while others seem to freeze, not moving at all. Some make a lot of noise, others are completely quiet. Because the reactions differ so much, there is no general rule that you can apply to know whether your girlfriend has come or not. The only way to know is to ask her. Do this outside the bedroom, when you have time to talk. If she doesn’t come when you finger her ask her what you could do differently. She might also masturbate in your presence so you can see what kind of stimulation she needs in order to climax. But remember that not all girls know how to come. It is possible your girlfriend hasn’t had this experience yet. So not coming to orgasm doesn’t imply she doesn’t enjoy what you are doing.