Kulga This has been discussed a few times. Glombersik I presume you don't mean a simple list of "friends" You mention Following a user (similar to following a thread). Anything else you'd use "friends" for in a forum? Private messaging is incoming (at some point soon) which may be useful for that Good thread for that This may also be a interesting read https://discuss.flarum.org/d/2068-types-of-threads-flarum-as-a-discussion-engine
Digital You can continue the discussion about "follow users" here: https://discuss.flarum.org/d/364-follow-users