actualy purva was already engaged to amar wid whom she was supposed to marry,but during der wedding prepration der parents expired due to wch d wedding was delayed,n on d other hand smriti was suffering from mental disorder so she was send to mental asylum for treatment,,during dis time period,mihirs mom chose her frnds daughter for mihir so dat he may remarry dat girl wch in turn vl take care of his son n prem too,but at d wedding day purva overheared d planning of dat girl n her mother dat she was juz marryng mihir for his property,n money...at dat tym purva tried to reveal d truth but mihir mom didnt believed her,so in order to save mihir n her sisters son prem,she took pheras wid mihir,wch after wedding was revealed to every1 dat purva has married to mihir,n in dis way she became his wife....
hope i hav explained u properly😊