Why is he suddenly acting different?

I'm 12 and so is my bff and he suddenly just changed. He used to treat like a boy but now he's treating me like a girl but idk why. he takes more notice of wat im doin or wearing or playing and other junk like tht .and now he's offering to let me lean on his shoulder. i mean wats THT about. it's weird. someone tell meh why cuz i think my bff was abducted by aliens right now