Isn't the relationship of this couple like the first couple? Is this necessary?

Well there are a few differences.
The uke whatever his name is is literally being manipulated and convinced to have low self esteem and has no idea what's going on
While azusa is being manipulated kinda by that deal he had with karino but knows what's going on. And karino want azusas self esteem to stay high and mighty. It seems he likes competition

I'm not saying they're exactly the same just that they're similar enough to seem redundant in the same manga for me That's what I felt when reading the chapter. What you said made me think the mangaka is trying to contrast the relationship with the main couple by making a similar one with the uke being manipulated and the other not. I still think I can do without this though so I still think it's unnecessary. I feel the plot isn't going anywhere.