1 - Pashu was probably talking to Nikita "tu ne shaadi karli" as they are all shocked to see her with Ved but they threw that in the promo to throw off the viewers
And/or
2 - Ved doesn't "marry" Nitika he just brings her home to Toasty and Tej to figure out what can be done about the matter that happened with Rajan.
We don't see any sindoor or mangla sutra around Nitika 😛