26 years old, and this very long, significant relationship ended only 3 years ago, and it was complicated because she moved.. I am almost twice your age, so as an old lady I can say I’ve been in your fiance’s shoes, and I’ve been in your shoes, and I’ve been the ex-gf’s shoes. I’ve learned that we are all a work in progress and all relationships are a learning process. At your age, there’s still a lot to learn. This can be a great opportunity for you to know your man better and be clear about your boundaries.
Your fiance is flirting with the “what if.” That’s why he kept this from you. He needs to learn that, if he feels the need to hide something from you or omit something or fudge the details of something…it’s probably because it’s not the right or respectful or honest or loving thing to do in the first place. And that should give him pause and send him right to you to talk about it, like, “hey, my ex is back in town and I want to catch up and see what she’s been up to. What do you think?”
That conversation could bring you closer together, if he can open up and, for example, tell you he was really messed up when she moved away from him after all that time together and how it fucked up their relationship and that was hurtful so he wanted to see her to brag about how happy he is with his fiance and his life… Or to see if there was still anything there and to do a gut check on what he’s thinking about marriage… Plus curiousity, like going to your 10 year class reunion…. Lots of conflicting, complicated emotions he probably hasn’t sorted through.
If he can talk with you about this, it would bring the two of you closer together. You also would be able to give him your own thoughts and feelings to consider. Explain how it makes you feel and remind him that if he doesn’t want to tell you about it, maybe that’s exactly the reason he SHOULD. Can you two have honest, vulnerable, raw conversations like that? If you can, you should talk with him and let him tell you what kinds of conficting thoughts he’s having on this situation.
My advice is to ask him why he wanted to meet with her, and was it weird, and is it weird now. You are his best friend and confidant. If he can confide his feelngs to you, this whole situation is quickly defused. If he instead becomes defensive, tell him it’s ok to feel conflicted right now, but it’s not ok to shut you out of it.
If I’m off base, then yeah, agree with all the PP, he has already taken several steps down a slippery slope.