IGN - Sheldon gets a girlfriend! Sort of. I mean, he already had one, but AFF has become increasingly frustrated by his lack of physical contact, resorting to assigning "skins" to her girl crush Penny. She goes out with Stewart (who I find adorable) and makes him jealous.
I mentioned this in an earlier review: If Sheldon is never really going to change, there is no way the increasingly socially comfortable AFF is going to stay with him. Though she did jump at the chance to be called the "girlfriend," and didn't freak out too much about the lack of physical contact, it can't last.