Muhammad Ghori and Prithviraj Chauhan had two battles First Battle of Tarain and the Second Battle of Tarain. In the First Battle of Tarain Muhammad Ghori was defeated. But the mighty Muhammad Ghori returned with greater force and in the second Second Battle of Tarain Ghori attacked Prithviraj's kingdom and defeated him. Prithviraj was taken as prisoner.
Here some historians say that no one knows what happened to Sanyogita. Some say she committed Jauhar.
But Prithviraj was alive, he was taken as prisoner so it is logical to say Sanyogita cannot commit suicide because her husband was not dead.
Some historians and writers say it with great taste that Muhammad Ghori knew about Prithviraj's beautiful wife Sanyogita because that time stories of love between Prithviraj and Sanyogita were very much popular. After taking Prithviraj as prisoner he captured his wife Sanyogita before she could understand anything. This writer here tells some hard facts about Prithviraj Chauhan http://uppermost.me/2014/08/24/prithviraj-chauhancertain-hard-facts/
Some Hindus accuse Ghori of raping but you have to take into account that in those days along with conquered land enemy women also used to go into the hands of the victor.
Muhammad Ghori was a true winner he defeated Prithviraj so every single thing that belonged to Prithviraj his money, his kingdom and even his women rightfully went into the hands of the mighty Ghori and he had the right to do anything with what belonged to him.