Anu, I also want the first reason to be true!! When it comes to Barkha I become a sadist.😈Personally I wish the first reason come true. It will be the right punishment for Barkha . She poisons Nikhil's mind with stupid theories on Sagar and Mili . It will be wonderful to see her reaction when she comes to know that she has a souten 😈 and maybe a couple of kids asking for their share of the property.
Like you said, the fourth reason seems more realistic. He is caught in some tricky situation and that explains the visit to club and hotel and its in some way connected to Ranavat. Assuming Adi is R's son, both Nik and Ayesha are now involved with Ranavat directly or indirectly and Inder is dragged into it being their father. I am sure Inder knows Adi's family background.