I met a very nice guy and we had a very nice couple of times hanging out. Yay! After our second time hanging out, he requested that I email his girlfriend to introduce myself and say thanks for letting me borrow him for a while. I agree that it's the proper thing to do, but I don't know what to say. This is apparently her first polyamorous relationship, and I'm inexperienced enough with poly where I've never been in this situation.
So my question is: if you were in her shoes, what would (or wouldn't!) you want to see in a message from me? Maybe I should just keep it really bare bones? And stop overthinking everything in my life?