LDR

Okay so my and my girlfriend are both 16 and we've been long distance for 1-2 months now but have been talking for 7 months. Long story short she has this guy friend she talks to that goes to the same school as her even before we started dating and apparently he likes her and she knows that. She says she has no feelings for him and she just "finds him fun to talk to" and he's a "comfort person" which hurt me a little because I'm supposed to be that comfort person. and he doesn't even know we're dating. I'm not even mad at the guy I just feel bad. Shes been keeping our relationship a secret even though I've already told my friends and family about her. I'm not afraid of her cheating on me or anything I know she loves me we're always on call together even when we're busy. She shows me her texts in screen share without me even asking and texts people I front of me, again, without me even asking and we sleep on the phone too. Can somebody really do all that without loving you? Even as were both in school were still on call muting ourselves but there. But I'm just so confused. We're planning on meeting in the summer. am I overthinking and being immature? I just don't get how she doesn't see a problem in talking with somebody you know has feelings with you and is actively trying to get with you when you're in a relationship. I want to tell her about this but I don't know how she'll react.