TL;DR there is issues in the friend group and I don’t know what I should do in this situation and if I am in the wrong.
My friend (Katie) started dating this guy (Eric) right after she got out of a 2 year relationship with someone else, Eric joined our little friend group. After she introduced him to everyone in our friend group, one day we hanged out with everyone and me (Emma) started talking to him (Eric) on the side to get to know him as a friend. We both realized we needed a gym partner so we sent up a day to go to the gym together. (This conversation was had with Katie and she knew about us going to the gym together and was fine with it.) After we went to the gym together, Katie started feeling a bit jealous because we went to Wendy’s after the gym because we were hungry but that’s was all we did. Eric had a conversation with Katie saying nothing was going on and that he saw me (Emma) as a little sister.
Eric felt comfortable with the friend group (mostly because he knew half of the group from school) so he started hanging out with the friend group a lot. We went out to a restaurant after our friend graduation and Katie kept side eyeing Emma and Eric even though we were both on the opposite side of the table. Katie started feeling jealous again but we assured her it was nothing and we weren’t talking at the table. Katie wasn’t jealous about it anymore later on and never spoke about it again. I truly thought nothing of it I only saw him as a friend and was just happy she was in a relationship and I was very supportive.
Fast forward to now, Eric and I (Emma) went to the gym a couple of times now but today was different. I can tell Eric was becoming a little too close to me but I pushed it off. After the gym we went to the park to chill and to eat our bagels we previously bought before going to the park. As we were sitting Eric was telling me about his relationship problems with Katie and that he was about to break up with her last week but Katie started crying as Eric would tell her the reason why he wants to break up with her is because she doesn’t care about his feelings and they don’t communicate well. And how He got his feelings hurt by Katie multiple times in relationship and Katie stated that she will change multiple times and she hasn’t and Eric also feels that way. After this conversation Eric started getting close to me again and it made me very confused because I didn’t think much about it until now and it got me overthinking. So I decided to be straightforward and ask Eric if he saw me more as a friend and he said yes. And honestly I was shocked and very confused. He did show me alot of signs but I truly didn’t think much of it and saw him as a friend I could talk to. And he now wants to break up with Katie by the end of the week. I told him I felt really guilty as I felt it was my fault but Eric said it wasn’t my fault and that he been planned on doing this. Should I tell my friend Katie that he plans on breaking up with her? What should I do with Eric in this situation as I still see him as a good friend? What should I do in this situation?