There is a saying that goes "everything in dreams is about sex... except sex".
I don't think that is true but i also wouldn't assume this has anything to do with sexuality. Dream interpretation isn't a science, but sex in dreams is often about absorbing or rediscovering something for yourself that you see in someone else or from an outside source that is symbolized by whoever the object of the sexual activity is. Nobody can really tell you what the dream is REALLY about. Dreams are influenced more by the mind they spring from than anything else. There aren't any hard rules for what things mean.
Journalling sometimes can help. Noting stuff from your day, feelings, worries, plans and dreams can give you sort of like a dictionary to find similarities or themes. Also, sometimes people figure out that they're actually gay even after having reasons to assume straightness before. No matter what though, this dream doesn't have to mean anything to you if you don't want it to. Good luck.
Lots of crazy dreams.
Also, assuming i was straight but then figuring out I was actually really gay and just didn't have the context to understand that I was.