He wants to kill Sanyogita because she is the only daughter of Jaichand. He has got to know that Sanyo loves Prithvi. Now suppose if Sanyo get marries with some one. Then after the death of Jaichand, Jaichand may give his kingdom to his son in law not Jaimal.
Thats why Jaimal don't wish Sanyo to get marry with Prithvi and keep trying to create prob btw Jaichand and Prithvi.