Girlfriend confusion?

okay well i have this wonderful girlfriend and i really love her and she loves me. but sometimes it seems like she likes my friends more than she likes me, like she seems more comfortable and has more fun with them. it's kind of making me a mix of sad, upset, a little jealous, and almost a little spiteful. i mean, my friends are great but sometimes it seems like they don't care that i'm with her, and that. i don't know, do you think i'm being selfish? is it common for boyfriends to get jealous over stupid things? just give me your advice... by the way, this is partially just me speaking my mind, so like don't think you need to give me an answer or anything