Kudos to Taylor for being so mature about all of this, but there's some major girl code violation going on between her ex Joe Jonas and friend Gigi Hadid!

Gigi, a model and Taylor's Bad Blood co-star has been romantically linked to Taylor's ex, Joe Jonas since breaking up with Cody Simpson a few weeks ago.  Even though I'm fairly sure Taylor had a Joe Jonas voo-doo doll and wrote a bunch of songs about him after their bitter break up in 2008, it seems she's ok with Gigi dating Joe.

The couple joined Taylor and her new boyfriend Calvin Harris for a double date at Plan Check Kitchen in LA after one of Taylor's shows.  Joe claims that he and Taylor are friends again after he broke up with her via text message seven years ago.

Clap clap.  Good for them, but doesn't this violate the #1 rule of girl code? Thall shall not date your besties's exes.  I would incredibly pissed if one of my girlfriends went after one of my d-bag exes, especially knowing very well what type of person he was and what led to the demise of our relationship.  What about you?