???????

I'm married for a year and together for 7 years. We have a young child together. Who we adore. A male family friend of ours had a newborn 6 weeks old and is planning on asking his girlfriend to marry him. Yes we are all very close. Sometimes myself and this male friend might talk to much or get into each other personal business. To get to point I can't stand the fact that he is going to be with her. Be happy with her possibly have more kids with her. I want nothing more than just to be his friend so I don't understand why this bothers me so much. It's almost like maybe I think he can do better but at the same time I don't want him to be with anyone. I don't want to seem selfish because I'm far from it. I would never say or do anything to ruin his happiness I just want to know if anyone else has felt this way about a dear friend. And why do you think I feel like this?