I don't disagree with Nina
Prachi should not feel guilty because she is aware that he is her husband. But Milind should not have kissed her, especially since he thinks she is Neev's fiancee
In real world, if you do feel passionate towards someone else despite being engaged to another, it's always proper to first discuss your feelings with your fiancee so he/she is not under the wrong impression that you love him/her. Your fiancee DESERVES that respect. Once your fiancee leaves you (for obvious reasons), express your feelings VERBALLY to the one you love, and after getting her/his consent, it's ok to get close physically
Of course, since WE know that Milind IS married to Prachi, and his engagement with Bhootni is just a sham, we don't find anything wrong with his actions. But, thinking objectively, I agree with Nina that he over-reacted!
In fact, my respect for Milind would have grown if he had confessed his feelings for P to A, and told her, in no uncertain terms, that it wouldn't be fair to him or her if they proceed with the marriage. I was actually MAD at Milind for letting N and A assume that he was sad because P held his hand. HE didn't have the guts to accept that HIS actions had led to THEIR misery! But, of course, BT LOVES to complicate situations😆
All said, I ENJOYED SHACHI's chemistry in that scene!👏