Well, since this comment section is basically the forum for this pairing’s controversial discussion now, I guess I may as well say that in my opinion, Mai gets hate not just because of her “aggressive” behavior, but because she doesn’t get “likable” in a lawful sense before Ajisai beat her to the punch.
Comparison is some dangerous stuff, and in here it’s especially visible because the first two romance routes don’t get as much attention than the third (Ajisai), and once she stole the show (in a never-seen-before-in-this-manga and healthy/sweet way), others possibly couldn’t ever come close.
But still, Renako wants the best for everyone, and on top of that she’s still at a loss about what to do with “Romance”, so she will try her best to be on great terms with all her friends. In the progress (which was kickstarted by Mai herself, so in a way, a large part of Renako’s assertiveness was because of her) she get to have a better lifestyle and a better group of friends.
I also like Mai a lot. Mostly because she’s incredibly honestly emotional and competent, not to mention romantic and genuine just to get Renako’s approval. I guess for this kind of pure unfiltered go-getter, I just can’t help but root for her to win.