Fight For My Way would be a drama that fits what you're looking for.
Childhood friends, same friend group, live across from one another with their friends.
One night stand: none
Love at first sight: none
ML realizes his feelings first: Kind of? The FL did have a crush on him in the past, but she had given up on it long before the drama started and never told him. The drama starts with her in a relationship with someone, it takes him a while to realize his feelings but you can see from his actions that he is falling.
Slowburn: Yes, very slow but not excruciatingly so.