1. Because Noina already informed Mihir day before the wedding that Tulsi didn't want Mitali as her Bahu.
2. Mitali already knew Angad proposed Vrinda, and he would marry her anyway as Noina collected proof - don't know how- Angad proposing Vrinda with Tulsi being present there (but Tulsi there was to take Angad away from Vrinda).
3. When Mihir confronted Angad over eloping with Vrinda, Noina showed the video, presenting as if Angad and Tulsi had planned to break the wedding in the altar, ruining Mitali's reputation and Noina's too.
4. Vrinda’s mom made it difficult with her greediness.
5. When Mihir threw cheque book on Vrinda’s face, Angad defended Vrinda which enraged Mihir more as he thought his son is defending a wrong girl over his father. And it happened thrice in the same episode. Mihir insulted Vrinda -> Angad defended Vrinda.
6. Pre leap it was shown both father and son wanted to mend their relationship, once it was in the episode where they met at the market and another in a restaurant where both father and son defended themselves but everytime both backed out due to. Like Mihir thought he chose Vrinda over him and Angad for he wanted to prove himself in front of his father.
7. Post leap, Angad hates him because he cheated Tulsi and Mihir toh doesn't care about anyone else.
4