What does it mean when you dream you scratch and bite your boyfriends face after you saw him making out?

It means you are angry, disappointed, hurt and that your boyfriend does not consider your relationship to be exclusive. If he has declared his intentions to be only with you...and you only with him (including in the biblicalsense) then he has betrayed you.

If your relationship is just casual, why would either of you want to be exclusive?

You now feel you can't trust him and when he comes to you with some story or promise for the future, just understand that once the trust is broken, you'll never feel secure with him. So don't buy it. Now might be a good time to get back out there and see if you can find a more honorable man. Yes, they do exist but you have to be picky and you'll find him.