Jo and Alex need to be done.
I never liked the couple and always thought Jo was too young and too immature for him. She keeps way too many secrets, creates stressful situations, picks fights, jumps to conclusions, and runs from problems. I had hoped Alex would dump her sooner. I truly hope they don't get back together after this mess. He has a habit of going for crazy chicks. Jo is no better.
I understand that Alex is the one who went postal on De Luca and no one made him beat the crap out of him. However, from the finale, it totally looked like Jo and De Luca were fooling around. I'd be pissed too if I walked in on that. And it looks like it was retconned by the writers that Alex thought De Luca was taking advantage of a drunk Jo, so Alex was trying to prevent what he thought was rape. So in either situation I can definitely understand why Alex snapped. The thing is, ALL of this could have been prevented if Jo was just honest about her past with Alex. They've been together for about 4 years. Instead of being completely honest, she drew that whole marriage proposal out forEVER and refused to even give an answer and picked fights with Alex over Izzie and other asinine reasons. He put up with her sh!t. He gave up the house for her to live in a sh!tty loft. And Alex still stuck around through all of that drama. All of that stress and resentment finally snapped when he saw her and De Luca together.
During Season 11, there was hinting of a Alex/Maggie thing but it never happened. Maybe this will resurface this season since Maggie is single now and Riggs is definitely interested in Meredith.