Vihaan and Rachna

Having missed more than a few months worth of episodes I was decidedly confused when I returned and saw two things:

a) Rachna walking, talking and acting like a wildcat

and

b) Vihaan being head over heels in love with her.

Just three short letters.

W*F?!

What did I miss with these two?!

Can someone please explain what happened? :O I'm more interested in these atm than Gunjan and Mayank.

Well it would be clearer if you told us when you stopped watching.