Questions about Jo & Alex

I watched the episode where Meredith & Riggs were on the plane then didn't watch the last 4 episodes of this season until yesterday. I'm a little confused about what's going on with Jo and Alex. Are they back together? And are they living together again? It didn't seem like Alex lives at Meredith's house anymore, but I don't remember them getting back together. I'm confused. And why did Alex go looking for Jo's husband? When did he even find out her real name? And what was Stephanie talking about when she told Deluca that he made a grand gesture to Jo and should now just drop it. I remember him having feelings for Jo and telling Stephanie that while she was having a breakdown after that older patient died. And in one of these 4 episodes, he was going to tell Jo his feelings but she stopped him and told him not to. Did something else happen (that I completely forgot)? Did Deluca make a grand gesture?? I feel like I've completely forgotten some scenes or an entire episode!