Dear Fahi....We are talking about 900 years back and no kind of proof to proove the history,just Prithviraj Raso and its different versions and various historian's version of history ,so no one actually knows these answers ,all of us speculate...meanwhile it is said that they married young as teens and Prithvi was taken captive by Md Ghori and as the news reached Sanyo she commited suicide ..hope that explains.
Maybe you can do some google seraching on PrithviRaj aswell 😊