one minute they adore you, and want you to stay and talk to them and you see them the next day, and they won't even say hi, and if you're just like "hey" they look at you like you're a psycho! two days later, they're fine again, and back to flirting with you
Ok first of all there dear, girls and guys can both be "bipolar" and it isn't a term to use lightly. This disorder is a mental disorder that is a chemical imbalance in somebodies brain. Using that term to describe a guy who "just isn't that into YOU" is wrong and politically incorrect. If a guy talks to you one and day not the next that generally means they just aren't that into you, not that you are insane neither are they. Watch using mental disorder terms in a manner that does not fully pertain to the actual and literal meaning.