1.Khushi had applied oil in Arnav's hair when he was sleeping and in her haste had dropped some on the floor:
Oil here refers to Shyam (the slippery slimeball). Khushi applying oil in Arnav's head could refer to the many hints Khushi had inadvertently dropped about Shyam. She had addressed Shyam by name when he had called her on the phone. Arnav was within earshot and did hear the name. The day she found out about Shyam, she was so disturbed when she bumped into Arnav that he soon realised it was something to do with her fiance. Later she looked all shifty when she was introduced to Shyam by the rest of the family and she rushed out, much to Arnav's shock. Arnav knew that her fiance was a PG in their house but then like in the scene where he was sleeping when Khushi had applied the oil, Arnav was unaware of the turmoil in Khushi's life when all these things were happening.
When Arnav wakes up and sees Khushi closely observing him, asking him if he needs anything, he hurriedly tries to escape her and in the process slips and falls because of the oil:
Although all the incidents related to Khushi's mysterious fiance seemed unconnected at that time, now that he knows about Shyam's obsession with Khushi and her supposed interest in him, he should have pondered more about what had transpired in the past but Arnav's brain shuts out when he is angry. His hurry to get away from Khushi and his subsequent fall is a reference to the terrace scene where he reacted in haste on the basis of what he saw in front of him and in the process hurt himself badly. The culprit was the oil a.k.a Shyam. Arnav fell hard on his a** seeing which Khushi is as much hurt as him much like this post marriage phase where both Arnav and Khushi are hurting while the oil (Shyam) which was responsible for it all is unaffected.
2. Coming to the photo frame scene, we are told that Anjali broke the frame but Arnav took the blame.
Arnav has been deeply affected by what happened to his sister on her wedding day that it had left his innocence shattered much like the photo frame. Notice that the crack is over the young Arnav and not on the young Anjali. Anjali coped with the difficult times by spinning an illusory world around her but Arnav had turned cynical and ruthless. Although Anjali was in a way responsible for how Arnav turned out, although she did not do it intentionally, he took responsibility for the way he has turned out, showing no sign of remorse. Take him or leave him. This is how he will be.
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