Cumming TOO much..

Idk if this is just me or what but when I'm with my boyfriend, I'm ALWAYS wet for some reason. It's so wierd! We could be driving and I can feel that I'm wet! I get even more embarrassed when we start to make out and he starts to finger me. He looks at me all surprised because I'm already wet. Sometimes I just want to stop everything cause I'm so embarrassed! What can I do??