I love Prem Saanjh's father who is realistic about Saanjh-Arjun relation. He knows they are good friends and at no point Arjun will leave his friend Saanjh.
But like the ladies he doesnt expect the romantic angle of Saanjh-Arjun. Maybe as a man seeing Arjun's body language he feels Arjun doesnt see his daughter that way which the woman are unable to see.
Most importantly I have never seen Arjun gazing at Saanjh the way a man will gaze a woman if he is romantically inclined with her. Mostly his dealings with Saanjh is platonic.
Now the second part, arjun and saanjh can change their relation. Yes saanjh can confess her love and then maybe he will feel for her and a relation will start. Or Arjun will accept Maya's proposal and his relation with Saanjh can detoriate as Maya is not going to allow Saanjh anywhere near Arjun.
But the problem here is Saanjh herself. See a woman need not be obsessive like Maya but as a wife I can very well tell I wont be comfortable if my husband is with a girl who has romantic interest with him, even though he doesnt have it. Any woman can feel that insecurity.
So if Saanjh has to be back in Arjun's life Maya will allow her only as Arjun's friend and she needs to be absolutely sure nothing beyond that. Here the reason is Maya's dad's mistress. Her father has cheated on her mom.
And I feel this will be where Maya can manipulate things paving way for Ayan -Saanjh so that Saanjh is eliminated from her dictionary. I mean she need not kill saanjh but a girl like saanjh will not cross the threshold of marriage. And Ayaan is not a bad boy. Vandana can be happy also. She got Saanjh as her bahu. As Arjun has never considered Vandana his mom.