Also Sahir is under lot of pressure due to the MMS blackmailing of Rehmaan ... so lets keep that in mind too .. he can now go to any extreme to make sure Zaki-Sam marriage happens even if it means faking love to Aarzoo I guess
Article also says Rehman sends Zaki to terrace where SaAz will b there .. so if Zaki sees SaAz together , he will think of Aarzoo as two timer too since he assumes Aarzoo loves him and so out of vengence he will agree to marry Sam ... Thats the trick played by Rehmaan and Sahir I feel to make sure Zaki marries Sam ... they will prove Aarzoo is bewafa to Zaki.. errr ...
It mayb temporary butchering of Sahir ka character ...sighh ... he may feel if Aarzoo can b bewafa or dhokebaaz and two time both brothers , why cant I play with her too