A friendship held together by hating the same person falls apart the day that person stops mattering.

A shared enemy makes a fast bond and a thin one. Talking about someone you both dislike feels like closeness because it is easy and there is always more material. But the glue sits outside the two of you, so when that person transfers, graduates or just gets boring, nothing is left in the room. You look at each other and find you never built anything of your own.

Try one conversation with that friend where the third person never comes up. If it goes flat in five minutes, you have learned something useful and not fatal. Start over on what you actually like.