1) After Sashi threw the ring Khushi knows that her father isn't happy. So when she does find out the truth she'll know that she always has/had her father's support + she might confide in him.
2) For quiet some days everyone was like women of IPKKND are dumb but our Khushi proved them wrong by putting 2 and 2 together. I guess thats why out Arnav Bitwa is falling for her
3) Shyam knows that now he can't do anything to stop the wedding as he knows that Akash has strong feelings for Payal.
4) Subconsciously Khushi came directly to Arnav meaning when she has no other way to deal with Shaym's reality she will confide in him. (plus it was cute the way he was asking her and in the end "Koi baat karni hai, Our Arnie is dying to talk to her about ANYTHING "
5) As always Shaym's happy that he got his way by clearing and making sure that no other people are coming. that way he has kept Angli and Khushi happy as they both won't know a thing
BUT WRONG AS TODAY'S EPISODE PUT HIM THE WORST POSITION EVER
6) The way La showed her necklace to Khushi showed that she was a little bit jealous