Why is it Deepika-Katrina can be considered a rivalry but not Ranveer-Ranbir or Ranbir-Vicky?

We've always heard about Deepika Padukone and Katrina Kaif's catfight. Both of them have a rivalry that is well-known to the public. Many individuals claim that they are fighting because they dated the same guy, but none of their new boyfriends is enemies of their old boyfriends; instead, they are excellent friends, but these actresses continue to fight for no reason. There has to be a purpose for it. What are your thoughts on this?