At this point, I just consider it part of their story. Kuhu said something similar herself at some point, whenever their relationship actually moves in any direction, either/both of them are sucked into some drama or the other -- mostly revolving around their sibligs' turbulent relationship -- and their relationship progress is put on hold. It's happened again and again from the beginning (I won't go into examples here, but happy to talk more if anyone's interested).
In the two months that Mishti was away, Kuhu managed to get the divorce underway, sort out her future plans, and start her business, because she had the time, space, and support to do so. As soon as Mishti came back, so did the drama -- NishMish attack, Meenu showing up at the offisite, Mishti disappearing in the jungle, Kunal spiking the drink, Mishti revealing his birth truth and now, this rushed marriage where she sees her cousin throwing himself into a loveless relationship. She has a connection with every, single person in this complicated situation and she's trying to be there for all of them -- so where is the time to think about her own situation?
Similarly with Kunal, Meenu tells him, if you don't spike the drink, it means you don't care about your family and we're not your priority. Abir says, now that you did this you don't deserve to be my Nanko. Now on top of that, Parul says, I don't want to call you my son. Kunal is so busy running around, proving to every member in his family that he "deserves" their love, and that they are his priority, that he has absolutely no bandwidth to think about what he wants for himself.
I would love it if these two would just say chuck it, and focus on their own problems, but the characterisation is convincing enough that I can see why they won't do that. So we must be patient with our two dunces who tend to put their own feelings lowest on the priority list.