its stupid how complicated it all is.
looks like what I've done is actually allow his account to share games on MY computer but not his as it doesn't show up in the list of "manage other computers" like you would expect.
I'll have to go to his mums later and try to get it working again... ironically steam says I last shared my library today but doesn't say who accessed it... probably because he just logged into my account because it's far damn easier than this crap
they should have done it so you just sent them a share request but I guess this way stops people sharing games with people they don't trust
I agree, it seems ludicrous not to have made it part of the right click context menu when clicking on a friend in your friend list.