Fiancée wants to hang out with another girl while we’re on vacation - HELP

Hi ladies, can’t tell if I’m overreacting / PMSing. Need your guys’ advice.

I’m on vacation with my fiancé and we’re in Paris. We got engaged here in May and we’re enjoying a walk in the rain and I asked this female tourist to take a picture of us. We all talked for a while and after we parted ways my bf was like “we should have asked her to hang out with us” and I was stunned and didn’t know what to say, I was like “oh ok”.

Then he brought it up again like 5 mins later— “we should have asked her to hang out with us- it would be cool to hang out with another tourist don’t you think?” Like he was upset almost that we didn’t hang out with this girl. Who we never met and was a stranger.

And I didn’t really say anything... I didn’t what to say

Am I overreacting? Or is this strange??? What should I say?? Help!!!