I am seeking opinions on best way to handle this.
Background: M30, 2+ years redpill, read sidebar and basically all of the books, lift heavy religiously, low bf% (4/6 pack depending on day), overall good job of leading and OYS- of course always trying to improve, sex 7/10, been together better part of 5 years (3 before that), 1 yo kid, getting married soon
Here's my dilemma... fiance tells me about going out to lunch with her girl friend and a guy friend. Both mutual friends of mine through her. I hung out with guy a few times a couple of years ago, see girl every so often. Guy is not a real threat, objectively multiple points lower than me as far as SMV. It came up years ago while hanging out (from her girl friend, same one at lunch) that "oh this must be awkward for you, since they fucked in the past" or something like that, which I was like ok who cares and went on about my business and had a great time, maybe even better with the mindset of knowing I was the one who got the girl. My SO denies this past history. Whatever, AWALT.
Fast forward to yesterday, my SO calls me on the way home from work like usual and is telling me about going out to lunch with these two. Going on about how this guy is getting married, living conditions, etc. a little giddy in her tone. I just go with the normal "that's cool, how interesting" responses. I then tell her about something unrelated and she flips out for not including her on it. I told her I was making an order days ago and tell me what she wants or I am going to order without her. Gave it a few days and made the order - she flips out and does a little girl tantrum and in essence hangs up. Awesome, now I have some peace and quiet before she gets home. I only mention this because this action is not typical for our conversations.
So from there, I have created a conflict in my own mind and would appreciate some opinions on the matter. I'm kind of stuck between two thoughts: 1- Who cares, you're the prize, it's your turn and the odds of this guy getting one is slim to none, if something was going on she obviously wouldn't tell you about it, and if she does oh well, lots of better fish in the sea
2- No, I need to set this as a boundary. Obviously it makes me somewhat uncomfortable and is a sign of disrespect in my eyes. If I let her disrespect me like this now, I could be giving her keys to a cuck-mobile to try and run me over with later.
Normally, I'd just keep this to myself, but while I was evaluating the best course of action to take internally, I was not being "overly" affectionate. Keeping it more to logistics with her. This apparently set off her radar and now she is freaking out that something is wrong. I don't believe I was showing butthurt, because really it isn't bothering me - I'm more concerned with making the mistake of not setting a boundary early on if needed.
I tried searching old posts, but didn't find anything directly related to this and kept getting /relationships results and they were only good for laughs. My SO never dated this guy, but I do believe they hooked up in the past based on what her friend told me. Am I making a mistake by letting it slide or is this an opportunity to set a boundary? I know mate-guarding is unattractive, so I do not want to come off in that way. I don't think this is "next" territory, but I'd love to get some outside opinions. Thank you.