AITA for getting along with my friend’s boyfriend?

Hi!! This is my first ever post on here so sorry if the writing is a little iffy… I (16 at the time, F) was invited to hang out with my friend (18 at the time, F) and her boyfriend (19, M). We went to the mall first and everything seemed to be fine. (We’ll call my friend Sam and he bf Jack) Jack was a good guy, super friendly and funny. I thought he seemed really good for Sam. We ended up in Hot Topic, looking at all the random things we wanted but didn’t need. Jack picked up a little among us blind bag and showed it to us asking if he should get one. I laughed and told him we should all get one as a “token of our friendship” I was mostly kidding because I hadn’t known him very long but he bought three of them anyway. Once we were done at the mall, Jack suggested we all go get dinner since Sam was getting kind of moody. We went to a local mexican place (so so good) and we all just chatted while we ate. At this point I’m having a pretty good time and definitely approve of the relationship (the whole reason I was there pretty much). Once we finish eating Jack and Sam drive me home. I open up my little blind bag and show them the among us guy I got. We all laughed at the funny little plastic toys and then I said my goodbyes and asked Sam to hang out again soon. She said yes and seemed totally fine at the time… That is until about a week later when I find out Sam has blocked me on almost everything without a word. I wasn’t too put off at first as I know she’s done this to many people in the past due to mental health problems so I never got in the way. I brushed it off for about a month until I was hanging out with a mutual friend, Taylor(17, F) and she told me everything. Apparently Sam thought I was being way too friendly with Jack and that I was going to try and take him from her (which would be illegal as I was 16 at the time and he was 19.) Sam decided she’d rather break off an almost 5 year friendship than “risk” losing some guy she met on Tinder a few months back.

For context: This story is from a few years back but I wasn’t on Reddit then and it still doesn’t sit right with me.

So, am I the asshole? (Feel free to ask any questions! I might have left out some details on accident 😅)