First of all i dont think Gauhar and Tanisha know and if they know , then they r probably just doing it for the show...
As in ur second point, i think it is different with actors than with ppl in "normal" professions, the women at home know that its just an act..
Armaan - well i think he is just very obviously playing a game.. he is not at all emotionally attached by Tanisha, but likes the fact that the girl has some hope and that for does put up a fight with everone for him, she is doing his dirty work and being attacked by others for it.. so for Armaan it is a Win-Win situation!
Kushal - if Gauhar is going crazy about a mug, y would it bother Kushal's gf?? That is Gauhar's problem at teh end of the day. If Kushal s gaining popularity by being good friends with Gauhar, then its good for him, y would his gf b bothered. He is not doing anything.. Gauhar is far more attached than him..
I personally dont see a prob in my bf hugging his friend and all..u cant b with a person it u dont trust them i believe...let them have their fun in life.. even flirting is ok... i mean at the end of the day if he wants to cheat i wont b able to stop it anyways... as long as he is honest and does know where to draw the line, everything is fine...