So last night me (m29) and my long term girlfriend (f31) were having a conversation about how lots of fruits when cut open look like vaginas, she asked how I'd know and I replied because I've seen enough of them. She then asked how it felt that I was the only one she had been with to which I replied that I would love to share her if she was interested and she said "get me turned on enough and I'll do it". (As in a threesome) Just for clarification we have a great sex life and we are open with eachother about things but I just don't know how to approach her to talk about it again as she is quite shy and reserved. Any advice on how to talk to her about doing it? And if she agrees to it how do I go about setting it up with her? I just don't want her to be uncomfortable.