Is it really a matter of honour of just the use of the friend system for something else? Is there any less honour in doing this than using your sub slots for 1* Cup ringers in your t14? I don't like it either but who am I to dictate to others

Happened to me more than once - but one guy that I unfriended in lvl 3 even got added back later, and is still in my friends list and supports me. Unfortunately, he failed to promote around S8 or so. He simply had decided at the time that supporting against me in a 2-horse race was part of the game and probably expected me to do the same. And I realised too later that I was just taking the huff over nothing.

Last season too I got requests from 3 teams who were obviously my rivals alts - so I rejected. This season when we had different leagues he made the same requests again - I accepted them all and he supports me and it even turned out that the lvl 12 team is an alt and I got a fb friend request from his main - so now I have a new lvl 36 friend

Sometimes through rivalry grows friendship - but I'm pretty sure that if we (his alt) get the same league next season 'all bets will be off' >.<. >.<