Man, we're still arguing about this? Look, I know some people think Serena's aggression took something special away from this ship, but I don't believe that's the case here. In fact, an argument could actually help bring them closer, maybe help them realize how much they need the other. I still don't know what their big argument could be about, but I'm pretty sure the resolution will end in a big hint. Maybe even from Ash's side!
I'm still not sure why some people think Serena getting after Ash in this episode "takes something away" from their relationship. I mean, it's not a new concept..most anime's have the love interest of the MC get mad at whatever he may do. I found the scene kind of cute? I dunno maybe it's just me.
It's also worth noting she's the only one in the group to have gotten upset or disheartened with him. Clemont and Bonnie sure don't.