She is depressed because you're paying attention to your friends and not her.
If you have your friends over she'll get pissed about it, but not tell you.

Girls are very complex, sinister, and fucked up. Learn to read them asap, and try to work them from an angle. Use their own tricks and traps against them, also don't try showing her the truth, or what's right by using logic. Logic goes out the window when dealing with most women.

Not that all women are this bad, just 98%. The other 2% are probably reading this forum.