First of all, this new MU is very logical and likely, but its a bit too predictable for IPKKND. Remember how we thought the same thing would happen when Shaym left his dhaga hanging on ASR's cupboard.
Second, Shaym already got the imprint of the key. Soon he will have a key to open the locker. Most likely, he won't leave any signs of him being in that locker behind.
Third, even if it happens, I don't think we should be very annoyed over it. Its not worse than thinking she is having an affair with a married man. Things always get worst before they start getting better. And I think a lot of us would be a bit disappointed if the MU went out without Arnav screwing up royally once more as his repentance will be greater later on.
So cheer up, it probably won't happen and even if it does, it will last for a couple of epis only before Arnav finds out the truth.
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