As much as I love Nine, I think its also a good chance for him to learn that Melissa isn't some glass doll to be protected or some god to be idolised. Mel is Mel. Although it comes from a place of good intentions (pat pat the good boi), Nine needs to learn its a mutual relationship.
I didn't mind Nine crying in the beginning, because it was just him being extremely grateful towards Melissa. Although it just kept happening more and more with every little thing which got me annoyed. I'm glad that Melissa is now aware of that and his overprotective behavior.