This is my opinion on mates.
I'm not trying to upset or target anyone at all. It's only my opinion.

I think mates are fine to have, if you do it the right way. I've learned from my past mistakes with mates on here. Squeegie had four! XD; But, I've learned. The first three were very random. I hardly knew the other deer at all, but I thought Squeegie having a mate would be 'fun'. Nah. It wasn't. The first one only lasted...like an hour. The other two were just depressing. I got really upset over them.
Don't become mates with another deer you don't know. First of all, it's unrealistic. Would you really go up to a complete stranger and say, "Hey! Let's be mates! 8D." No. Probably not. And second, it most likely won't last. If you wanna' be mates with someone, actually know them. Don't be their mate because you think it'd be cool, or you'd become popular on this site. Really only become mates if you think your deer and their deer would really be good together as mates. c:

XD That was strange, but. Ya' know, just tryin' to help.