I'd rather say that he is a human being afterall and can make wrong decisions or let's say do things at times in a wrong way though his intentions are good. He is a mature, sensitive and sensible guy, he stands by what is right but he went wrong in few instances (tell me if you differ on some of the following points)
He called Ananya criminal before really getting any proofs of that and we know that one of the main rules of law is that " a suspect is innocent until proven guilty"
He said he should only hate her, why should he? Even if she is a criminal?! Normally if you do things professionally why would you think you should hate her, you would catch her and let the justice take its course in a normal way, why would you have any feeling be it hate or anything towards the whole thing.
Obviously, we know that he was just fooling himself, he never hated her ever, not even when she married him dokhe se, he was just hurt then because she lied to him and hoped she was really honest and she did it really for him but he knew she was lying. He had feelings for her since day 1, but still what he was saying was kind of irrational basically because he was in denial mode. I know Ananya didn't give him reasons to trust her as she kept lying to him but still he can't outright judge her. I agree with what you said Mandy, in that bathroom scene when he saw the huge effect Ananya has in him, he said that he can't have humdardi for her as she is a criminal while in fact what he wanted to say is that he can't love her, first because he suspects she is hiding something, secondly because he felt he is betraying Juhi's memory, another reason is he wouldn't want to fall in love again and lose his love!. About Juhi, If we remember the day of haldi when he had that dream where Juhi put Ananya's hand in his, he went back to his room and and took Juhi's picture and talked to it saying that no one can take her place in his heart, he knew very well it was too late and that happened already but he kept denying it.
The marriage with Rhea was another wrong thing he was about to do, even if it was fake and even if his intention was to find out Dayavanti's truth. He was thinking then that Rhea is just a victim of her grand mother's blackmailing, yet he decided to go ahead and fake a marriage with her! what about what will happen next when truth comes out, what about the girl's reputation when people would find that it was a fake wedding?!!!
The same thing happened when he used her to prove Avni's innocence. Neil used Riya, it's not ethical, I know Riya is no white pigeon, what she did was disgusting (tarnishing a woman's repuation being a woman herself!!!) but what matters most to me is Neil's character and his principles, the bottom line is that he used her without her consent to prove his point and he published the pictures in a newspaper which made her reputation questioned. At least they could have shown that the newspaper was fake and he made it only for that purpose and there are no other copies of it that went to the general public, they could have also shown that he is well aware of what Riya did to tarnish Avni's reputation, so to make her understand her mistake he put her in the same situation she put Avni in , all this obviously without having the newspaper diffused. These few little details could have avoided me raising questions about whether the way Neil tried to prove his point was right or wrong, for me it was wrong because these few details weren't included, he could have called his friend Malini and with her consent made that whole act and obviously with no diffusion of the newspaper. That would have been ethical, as it would have been an act, the person involved aware of it, she being a cop would understand too.
He faked friendship with Ananya, he knew she was sincere about it, he said main hamesha tumhari saath hoon, ek police wale ka farz nibhate hoon, yeh dosti ka jootha natak kara hoon, tumse saach bolvane ki liye. Now I know he didn't have ill intentions, he never had, he really wanted to do his duty of a police officer but why say that he was faking friendship? did he really believe he was faking, despite trying to convince himself of that, he was very much involved emotionally in all this, he was telling his mind that he is doing his duty, but his heart always wanted to help her and trust her and at some corner of it he did, but she kept lying to him and that hurt him a lot, it hurt him that she couldn't trust him
It's complicated lool, his love for his duty was/is real, so was/is his love for her, but the way he did things wasn't always right and as many of you said he was at times too strict in his perception of right and wrong, in abiding by laws despite feeling that maybe she was wronged, it was only when he got a proof that Dayavanti can really be what they are saying since she wa ready to force her grand daughter to marry for money, that he stopped pursuing Avni and wanted to focus on Dayavanti to find the truth as he wouldn't want an innocent person to be wronged
Another thought is maybe the reason why he wanted Avni to tell him the truth and trust him is actually to prevent her from doing something wrong which has irrevocable consequences, basically to save her from her ownself!
Anyways I might have gotten some things wrong, I need to rewatch and observe things more clearly, moreover human feelings and psychology are very complicated, there is not one single thing involved, it's a combination of things.
He is a wonderful man because his intentions are good and he tries to do the right thing, I love that he is strong headed and stands by his beliefs no matter what but at the end of the day he is a human being so mistakes can happen, in his case mainly because it's a matter of perception and beliefs.