Why did charles marry diana if he didn't love her

Prince Charles wasn't allowed to marry Camilla because of her past, and so, instead married Princess Diana.

Diana and Charles meet for the first time at the Spencer family home

February 24, 1981-announces news of Charles and Diana’s engagement,

Charles is fully dating Diana’s older sister Lady Sarah.

According to Diana, they “sort of met in a plowed field” in the course of a shoot, so it didn’t precisely go down like it does on The Crown

During his engagement interview, Charles recalled assembly Di for the first time and questioning how “very jolly” 

Prince Charles and Princess Diana’s-That's was start crown 

but again, he was dating Sarah at the time. Like, there are pics and everything