"After Wonder Girl told Supergirl that the only reason they were friends was because she was her only remaining link to Connor, Supergirl also quit the team."     
 
 
So whats Wondergirl's deal?  I honestly don't like Cassie all that much (no offense to those who do), but she really annoys me with some of her behavior. 
 
She apparently flat out told supergirl that the only reason they are friends is because she was her last living link to her (at the time) dead boyfriend Superboy, which drove Supergirl away from the teen titans.  Now, did Cassie really mean what she said or was she just pissed off about something and got carried away?  Cuz thats a REALLY cruel and messed up thing to tell someone, especially to a girl like Kara who's still adjusting to life on earth. 
 
Also, Superboy is finally back and yet Wondie is apparently giving him the cold shoulder instead of getting back together with him (and this is the same girl who once joined a Superboy resurrection cult...really creepy). 
 
Oh, and she gives Rose Wilson, AKA Ravager, more crap than she does Bombshell, who willingly betrayed the titans and tried to frame Rose and then was allowed back on >_<

So can anyone here explain the circumstances and reasoning behind her attitude and actions?  Particulary what went down between her and Supergirl?

No one Superboy is getting a new girlfriend.

My impression of the situation is she had a minor teenage meltdown when she compared Kara to Conner. Also she still loves Conner but doesn't know how to act around him at the moment. When Conner died she was not in a position of authority within the Teen Titans,
and during the time he has been gone she has made some personal growth. She mourned his loss and began to move on, and has become more of a leader with the TT. She is caught between her feelings for Conner and her duty and responsibility and she is finding 
she does not know how to proceed. She has changed and she is probably wondering if he is still the same.

Im wondering if Superboy is getting a new girlfriend, if u look at the upcoming Teen Titans covers it seems to me Beast Boy might be leading. Meaning Wonder Girl might have realized that she is a little off and decided to straighten things out. So she might have dropped leadership to work things out with Superboy after he kisses who ever.

Cassie has her problems, but I have to say I like her way better than Donna Troy. It's hard to put my finger on it, but something about Donna Troy really annoys me. It seems to me that half the time she' written as some kind of Purity Sue, and the other half she comes across as a bitch in sheep's clothing. Also, there's her tendency to die and come back to life a la Jean Grey. At least Cassie is written like a real person.

I dislike the writing in Teen Titans more than I dislike the characters.  The Teen Titans have always been one of my favorite teams ... in theory ... but in recent years I have had a hard time reading poorly written (IMO) teen drama - and Wonder Girl is a victim of this.  I don't know why but I keep on buying the series,  I guess I just keep hoping.

I'm not sure if this was soon after Conner's death because if it was she was probably mourning and people do tend to say things they don't want to when they've lost a loved one. it's a simple fact of human life.