Crazy girlfriends

so me and my best mate were like two peas in a pod, we liked & dislikes the same things and one thing we’d always discuss were those girlfriends who act crazy with their boyfriends, cause our guy mates had girls like that. But now, my best friend has turned into this moody, annoying girlfriend who is always, without a doubt, getting moody, starting arguments & causing a scene about her boyfriend and it’s ALWAYS in public to a point where we don’t even like being near them when it happens. Now he, does nothing wrong, it’s like she has this switch and whenever we’re all having a good time she goes all crazy on his ass and its always for stupid reasons like “he doesn’t treat me like his gf” “his not acting like my boyfriend” the poor guy isn’t always hanging off her, kissing her ass and holding hands but he doesn’t act like he doesn’t bloody know her or isn’t with her. N she literally breaks down crying and causes a huge scene infront if whoever is there. Has anyone had a friend like this or know how to deal with it? I can’t just ignore her and let her go cause she’ll be all like “shes not acting like my friend” but then whenever we’re out and about it feels like we spend the whole time running after her making sure she’s okay and trying to sort it out. Everyone says she’s doing it for the sole purpose to get her boyfriends attention but I just don’t understand it and think she’s going off the rails, it’s just getting worst and worst each time .