<human>: Close enough to make me uncomfortable is my answer.

Me - Male, 21
Her - 19
Dating for over 1 year. No problems at all, normal stuff, no arguments, perfect really. I have another post similar to this but this is a bit more specific.

Basically my girlfriend has a friend she has never really hung out with, more or less met at a party twice - three times, she has mutual friends with him and all that, it's more of a Facebook friendship I would say.

Now she is incredibly open with people, and she says everyone but I think it's more her choosing, I don't know everything unless I ask but it seems with this guy, she's too open for my liking.

They talk about anything and everything, half the time it's sexual. Sexual in a way - how they style their pubic hair - what me and her have done/do/size of my genitals (I brought that up with her and said I didn't appreciate that, she apologised).

He's a really friendzone-y kinda guy and will post on her Facebook from time to time, and it's their in-jokes that really no one gets but her. 

I feel threatened by his relationship with her.

Sometimes I feel she chats to him more than me on Facebook, and when she is chatting to both she'll take ages to respond because she's probably more focused on his conversation.

How can I bring this up with her?

I would like to finish with - I understand it's her mind/body/emotions/thoughts and her choosing who she talks to and about what. I tell myself that to make me feel better but it doesn't work.

Could you distill the essence of the text into 1-3 sentences?
<bot>: My GF has a best internet guy friend who is accessible IRL, they talk about anything and everything and I believe he has feelings for her - no doubt she knows it. Makes me uncomfortable.