Honestly? Sometimes dreams are just dreams. I had a dream I was on a cruise once and the attendants were vampires who were trying to suck the blood of the guests. The other day, I had a dream about my ex boyfriend, and that I was kissing one of my other guy friends in front of my ex, even though I'm not in a relationship right now (and I don't think I have a crush on my guy friend lol).
Is it possible that maybe you're afraid of your boyfriend "finding someone better" than you? Dreams aren't usually premonitions, but sometimes our unconscious fears and desires can show themselves in dreams. This dream does NOT mean that your boyfriend has found someone else, but it could mean that you're afraid of him finding a new girl. Having a conversation with him might help lessen your fears. Hope this helps!