How is this supposed to work...?

My boyfriend and I have just recently got back together after a 7 month break because I didn’t want to put stress from school on him. In that time we both saw other people because we both saw it fit. I had travelled for my fathers work and made a new friend who is my closest friend yet. This new friend and I have had some romantic experiences together, as my boyfriend knows. My boyfriend is constantly worried that my friend and I are going to get together... I would never cheat but sometimes I consider what it would be like in a relationship with my friend instead of my boyfriend as my friend has admitted feelings for me. I feel like this mainly i think because my boyfriend is very closed off with me and is distant whereas with my friend I feel free to be who I am and I seemingly have more fun. I don’t know what to do... can someone help?