Mishti has always truly loved angad. Angad loves/d kripa, but hates her as well. So if Angad wants to get together with Mishti, for whatever reasons, I think they should - at least Mishti will be happy and she deserves it.
I know that there are not many fans of Mishti (I am not a fan myself but I do think that she desreves to be happy) - but Mishti definitely does not deserve Karthik