There are a number of reasons why some men don't like performing oral sex on women. It's a very individual thing. It could be an issue of aesthetics (taste or smell) or one of social conditioning (some men are conditioned to think it's dirty). I would strongly recommend that you discuss this with your partner if is bothering you. One thing I recommend to couples is that they bathe together before having sex. It's a great form of foreplay and makes both partners more aesthetically appealing to each other.

Melissa