Keep talking about it... I think that'll help. Especially to your GF. Seems you two have great communication skills with each other... be wary of slack creeping in, though.
I'd consider, were I in your shoes, doing more things w/my partner to create new images to flood my mind.
You got this... recognizing your rumination is a biggie.
Question, though: Have you ever discussed the situation with your buddy... who made the intro? Could your discomfort lie in that arena, maybe? Just a thought.