Another option will be that if Rajeev marriage happens than it can be without signing deal paper as in mandap to prove himself innocent he has to marry Nimrat without this paper signing condition . After marriage he will show tantrums which will irk Babita as she has planned to sign it from Dildar without Virat knowledge to safeguard Nimrat married life and Amruta spoiled it . She will feel they are not treating her daughter well because of that contract did not getting signed because of Amruta.
This leads me to wonder why Gautam was made to break his alliance with Amruta. Is it that Babita in anger (due to Nimrit marrying Shekhar) calls/threatens them to break the alliance or is it due to Rajiv-Ishika taking revenge or maybe instigating Babita to break Amruta's alliance to avenge her daughter's marriage with Shekhy? More likely the latter. 
I mean.. come on woman. He is about to put the ring, and she is chatting to someone offscreen. That was very off-putting.