Well you're a gold star here's is tarnished..... Maybe before you met? How long have you been together

Robert is the one who gave her cunnilingus that tickles and converted her to a lesbian.

Maybe she has a dog named Robert growing up. A really pervy dog.

Maybe Robert the haunted doll is now Robert the haunted sex doll.

Her vibrator?

it's entirely possible that it wasn't even oral sex in her dream. it could have been something completely innocent and different.

Maybe her cat Fluffybottom's real name is Robert?

Did you try asking your girlfriend about it when she was more awake. It seems like that’s really the thing to do. Only she knows...

I’ve had sex dreams about all kinds of people I’m not interested in in real life. Dreams don’t mean anything.

Maybe she was dreaming and talking half-consciously?