So my friend has been going out with this girl for about a year now, she's very emotionally unstable, whiny and in general just a bitch. My friend is getting really depressed and I know it's because of her, yeah you might say it's because I'm jealous but even his dad mentioned it to me. His dad tried to talk to him about it and he just told his dad to fuck off. I barely talk to him anymore because she's always there and I can't stand her, I don't if I should just leave them be or say something to him. He's stopped coming to football, stopped going out "with the lads" in general and when anyone does see him he just seems so depressed, completely changed. I'm really not good with other peoples emotional shit, I don't what to say and even if I should say anything. Any suggestions?