First of all I love preeran so don't hate me for posting this
-> preeta will get a phone call from her office that there is an emergency she has to come as planned by mahira and ramona
Preeta is about to go but rishabh will ask to drop her
Preeta and rishabh met an accident, their car fall down from khai and no where to be found
Luthras think that they died
On other hand...
Preeta and rishabh are saved by villegers and they thought they are husband wife seeing preeta's mangal sutra
RishTa's memory are wiped out but they believed that they are married and start living their life unaware about luthras
For rishabh it was love at first sight so he started loving her
For preeta marriage is everything so she will try her best to make it work
After some time for some work rishabh need to go mumbai and preeta accompanied him
Where they met luthras and karan hugs preeta seeing her there (this meeting will happen after a looooooot of episodes but i just simplified it)
Now RishTa knows that they are not married and now preeta remembers her past (where Rishabh does not)
Later on she get to know that she is pregnant
I know preeran are couple but somewhere at some point ekta will use this love tringle and siblings hating also because show 10 saal chalana jo h use 😬
But I think all these happen when preeta and karan will start living their life at their best