Like I was saying to another guy a while ago, this trip will in some ways answer a lot of questions and hopefully put some things to rest. It's just like when Logan visited after Sid found out. Em ignored him and then was never seen again. I think @Houlii is right in that maybe Bob is there to make some sort of amends. I doubt anything will happen between him and Em during this visit as there hasn't been a single sign of flirtation between them. After this visit it will prove that Em really doesn't have any feelings for Bob, there won't be any more sex between the two of them, and I can go back to not watching this apartment since Sid and Em's relationship is beyond mega boring.