I feel conflicted about possibly ruining a couple’s night

I was at a party last night, and I met a bunch of new people. At one point, I was sitting next to a cute girl who was there with her partner. The party game we were playing required us holding hands for a while which we did without fail. But more importantly, later when the party was on the porch, I sat next to this girl and we ended up having deep conversations about a lot of things. I don’t think we were subtle because one the flamboyant guy at the party kept poking questions at us. We were sitting close to each other with our arms and legs touching, and the conversation was as if there’s just the two of us. It was a great connection.
At a later stage of the party, her bf and her were literally having some argument in front of everyone but luckily drowned by other people talking. And then the bf disappeared for a while while she continued playing the game with us. I stayed away and just hugged her goodbye on the way out. Part of me feels terrible for not asking for her number but the other part feels bad for her partner. He was visibly sad when he came back.
But now I’m realizing that I have no way to meet her again as this mutual friend is leaving the city and I don’t have any contact information. Should I ask my mutual friend?

ALSO, when she was showing me song on spotify, “shower sex” shows up as my recently searched playlist. BUT I had accidentally clicked on it earlier when looking for shower playlist. So that’s an embarrassing memory I created last night.