Arnav has always been drawn to her childishness, naughtiness etc. as well...We saw him missing it in the friday's episode..probably because these things are missing in his life and she completes his life by bringing color into his..
Anyway, her childish antics will just make Arnav more fond of her...he will just miss her absence more when she leaves because he would have gotten used to her OTT behavior and taking care for him..and who knows, her pranks might just bring out the naughty child in him..