This is just a hypothesis which could be quite well of the track but I really felt it that way .
1) Sanskar might know about Kavita so he could not take Swara's acceptance as he knows that when Swara will come to know she will try to make things correct not for love . Again when he said "par yeh mera dil hai tumhare kareeb aakar tumse dur jaana mein bardass nahi kar paonga".
As he knows that Swara being selfless or mahaan will be ready to leave him after knowing Kavita's truth . He also said agli baar it means that she will not believe him that he loves him after knowing kavita's truth. This story will end like that means Swasan will end. When she said she will come back he was happy for an instant bcoz he wants Swara to come back.
He wants Swara not to stay in MM(either forced by Dp beautifully described by Kavya ) or he doesnot want Swara to know about the truth even when Swara asked him about AA he doesnot want Swara to dig further as it will create more tensions.
There is one more silly thing which I noticed the flash when Kaveri was singing was on dp then sanskar again when Swara said outside MM that she will show him that he loves him here was a flash which could say that he beleives inher love but is quite scared of accepting bcoz Swara might leave him after Kavita's entry
Now, it is going to be battle of Sanskar's sympathy &love. Actually then it is also a trust game for Swara. Again we will talk first true louu versus second true love.
2) He is a confused soul and is the tug of war between Swara and kavita So, he is behaving in that way.
3) He may be playacting bcoz he has understood that Ragini could do anything and wants Swara out of MM in any cost.
4) He is really confused and Kavita's entry will make him more confused and the serial could be dragged by making Sanskar swinging like a pendulam (which will make really upset). r
Ragini could easily manipulate Swara( to leave Sanskar) or Kavita(to marry Sanskar I dont want it bcoz anything can happen even marriage between unnecessary ppl ) or both. Kavita could also manipulate Sanskar that Swara doesn't love him as he is already in that confusion.
5) fortune ka besan ka ladoo ka kamaal hai ek saath ek girl friend free.😆😆
He may not know about AA but knows about Kavita or knows it is linked with him.
Bye tc.