People think we like each other but just friends!

Hello! I am in my early 20’s in college and I have made a good guy friend these past couple of months within a group project, he’s a year older than me. We have good banter, and we talk about relationships, life, a lot of different things purely just chatting to chat. I thoroughly like talking to him and we give off a lot of the same energy, but I do not view him romantically cause I know 1) he has a lot of emotional baggage and 2) it would ruin our friendship and 3) I don’t really see him in that light, I view him almost like an older brother.

Well, my group and I were working on a project over at his apartment, and we got some work done. Me, this other girl in our group (who doesn’t show up to class all the time to work on things, so naturally him and I just have gotten closer as friends) got the work done then spent a hour or so just listening to music having a good time and chatting. Our banter has been “flirty” but I have never really felt like it was romantic, it has just been a warm vibe. At first I did think he liked me in the fall, but as we walked out of class together more, I realized he was flirty and warm with everyone, and that’s his personality. He’s a great character to be around. I usually just reciprocate his energy, which happens to be warm and flirty. I have never once felt an inkling of attraction besides outside of friendship for him.
This other girl and I the MOMENT we walked outside of his apartment goes “So..how long have you liked ____?”. And I am tired and just honestly flabbergasted she phrased it that way to me. Like we are in grade school. I just said calmly “Uh I do not like him. He’s a flirty personality, and I thought he liked me but I picked up he’s just like that with everyone. We just have good banter”. She didn’t look convinced, and I just felt like I had to defend myself. Our other group member, didn’t make it tonight, and I asked him about it later (we are closer and known each other longer) and he said that me and this guy flirt hardcore during class, but there’s nothing to feel ashamed about. I genuinely didn’t pick this up! I guess I am making a post because I don’t want this to get back to my guy friend and ruin a good friendship because people think things? Let alone did he hear her out in front of his door? I just felt like I was in a corner. Now I feel like I can’t be myself and have to watch every move I do, because I am being analyzed, and I am a warm person to be around. Ugh. This is so childish to type out I’m sorry this is just frustrating me.

Thank you for any input.