Most Helpful Guy
It's a minor form of manipulation. It is a way to gauge your reaction to him talking about you in sexual terms, making you think of sexual encounters, so he can see how comfortable you are with the idea. Most of the time he won't have even dreamt it, he will simply have thought about the idea and is using the 'oh, it was a dream' as a way of pretending he had no conscious control over it.
But by saying something like "I dreamt of you in lingerie" he can see if you say "Oh, I love wearing sexy lingerie" or "Wait until you see it for real" or "Not bloody likely, pal"... how you answer will tell him a lot about your feelings for him.
It can be a bit invasive if you don't know the guy very well yet, as it's kind of pushing the boundaries of acceptability, but some women really like the attention if they are into the guy, so it can sometimes work to move things along faster.1THIS IS NOT RELEVANT ANYMORE
Most Helpful Girl
He is only interested in sex and he is trying to turn you on.0THIS IS NOT RELEVANT ANYMORE