I think my gf cheated on me based on a dream
Could you explain what your girlfriend did in your dream?
I dreamt about her making out with someone in the living room.
Dreams can sometimes seem very real. Even if the dream was quite convincing, that doesn't mean for certain that your girlfriend is cheating on you. You should have a face to face conversation with them and ask them up front to be certain.
I didn't believe dreams were real. If that is how dreams are supposed to be, then why bother having them?
You shouldn't be jealous or mad at her because of a dream, but having a conversation about it could clear the air and make you feel better. It's just a thought, something that would help fix how you're feeling.