Guys are also fearful that as soon as they say they love you, then the woman will relax and that will change the relationship and the woman will take the man for granted. That is hard to say. It will vary from person to person. Surely, the clitoris is the most sensitive and sexually responsive zone, but some women don't like direct contact because it is so intense. You might just need to ask her and experiment.
Sexual communication is really important.
That is part of your responsibility as a lover. So what I would recommend is giving her suggestions. There are really no exercises one can do. Penises are rather self-maintaining. You really don't have to exercise your penis.