Search Results: acting different around friends

My boyfriend and I have been friends for almost four years and we've been together for almost 2 years and a half. We are both a silly and serious couple. We have our moments where you can obviously tell we are a teenage couple, but we have our moments where some adults consider us to be a mature couple. Still acting like friends, we talk about almost everything, we are honest to each other most of the time and joke around a lot. As boyfriend and girlfriend, We are very supportive, caring, loving, understanding, and willing to each other. Lately, My boyfriend and I have been arguing over his best friend ( a girl ) who is obviously crushing on him and once admitted that she did (as well as trash talk me even though she never met me). I know he doesn't look at her in that way, but I don't trust her around him. I started developing a form of jealousy towards his best friend because she knows him longer and better. She knows how to handle him better in certain situations. After these arguments and my jealousy that started to develop, We started talking less on our phone calls, Our dirty jokes almost completely stopped, and our future plans started to sound like fantasy than reality. We still text each other normally, but when we talk at night, its like we are two different couples sometimes. Although on phone call we dont talk much, when we see each other, we have a great time together and things feel normal.

Is our flame dying or am I overthinking it? If it's dying, is there a chance to regain how we used to be.