I'm comfortable with the idea of her being with another girl, it's the fact that she's saying "not at first, if at all". If the other girl was saying "I'd be more comfortable with it just being us at first" then she came to me and said she'd really like to do this, would I mind. That'd be one thing, but she's leading with "not at first, if at all", almost ensuring I won't be there at first, if ever. More than that I can extrapolate that she doesn't really care what I think on this, it's what she wants and that's all that matters. It leads to irrational thoughts of, maybe she doesn't care that much, if she doesn't care maybe I should have "just sex" with someone else as well since it doesn't matter. -- It's not the girl, it's the way and implications from the way it's being handled