😉ok to answer most of your questions as to why he let them get married is because:
1. them getting married is a big blow to tulika and it will ruin her! veer's first revenge!!!
2. anu finding out after the wedding is more hurtful than before the wedding. Zindagi Bhar ka dard!! his second revenge!! for anu rejecting his love!
3. Nikhil will have the hatred and not love of anu and his kid for the rest of his life!! promo shows that anu is going to stay with nikhil but as a just his legal wife!!! and never make him happy!! this is Veer's Third revenge with nikhil for all the pain he caused him
so does that make sense now?😉