I'm wondering about that too!! What has he been doing in these eps??
Someone on tumblr
theorized that when Robin recovers "Marian's" purse, it looks like he
finds something in the purse that he is looking at and she speculated that it might make him suspicious. We know he goes to Walsh's store and calls someone and meets up with Rumple at some point. Maybe he asks Rumple for help and Rumple won't help him? Maybe he takes Roland and they go on the run from Zelena and up at that cabin? Or like you all said, maybe Zelena has him hostage? Fortunately ep 15 isn't too far away and then we might be able to start putting it together!