<human>: Oooooooookaaaaaayyyyy

So I've been dating this girl for basically a year, and we've had a really solid and happy relationship, for the most part.  Since we're currently on summer break, we've been seeing each other more often, and it's great.  From here on out, she'll be referred to as Gina.  But I've also been seeing my band more often.  And in my band is this girl.  Let's call her Joan.

I met Joan in November (about 5 months into my relationship with Gina) when she came to a band practice, invited by a mutual friend.  After a while, as we started to actually become a band, Joan and I became quite close, and now text very regularly.

This has started to cause some strain between me and Gina, mostly because Gina is thoroughly convinced that Joan has a crush on me.  I personally don't see it, but I've learned not to trust my judgement when it comes to people having crushes on me.  Gina is annoyed that I spend so much time with her (and, admittedly, I hadn't been spending enough time with Gina before we talked about it.)

A couple days ago, Gina and I had a discussion about this, and I agreed to spend less time with Joan.  But now Joan is freaking out about a gig we have coming up soon, and we've been spending more time together than ever, albeit with our mutual friend present, since he's part of the band.

Really, I'm just worried that if I keep this friendship up, it'll ruin my relationship with Gina, but I also want to keep being friends with Joan, and I don't know how to spend less time with her without hurting her feelings.  I'm very new to this whole "dating" thing, and I really want to keep dating Gina, but not at the expense of my friendship with Joan.  I don't know what I'm doing at all.  Help me out here guys.

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: Girlfriend might be jealous of my friendship with other girl.  How do I stay friends with her without my girlfriend feeling "threatened"?