Prithvi is just there to support Kripa. He doesn't want her to get hurt. Obviously Angad has hurt her so much and only Prithvi has seen the pain. Prithvi just doesn't want Angad to come close to Kripa, who knows Angad might hurt Kripa again.
I agree that Prithvi doesn't have to follow Kripa everywhere, but he still loves her and it's hard to see your love suffering. As Angad felt jealous over the phone talk, Prithvi can also be jealous of seeing ANgad and Kripa together.
oho happe tu vi na. u always have to be the sensitive one. Youre turning into a prithvi.