I recently learned the hard way that even pending friend requests count against the 80 (really only 79, since you appear on your own friends list.), even though neither you nor they receive any of the benefits of friendship. I reduced my list drastically in order to send a single request. This involved cutting perfectly good, active friends, as long as I knew they had requests left and would send me one in due course. I told them to send one right away so I wouldn't have to pester them later, planning to accept once the other thing was taken care of. A number of them did just that.
I was astonished to discover that those requests counted against my total. I had to decline these requests, even though I had solicited them. This was embarrassing, although most people affected took it with good humor. This is one of the only times, maybe the only time, I was genuinely furious at Inno management. I still am. This mechanic of requests counting against the total is spelled out absolutely nowhere. I did everything precisely according to the published rules; all I wanted was for Inno to play by their own published rules as well. This is a reasonable expectation. In-game support pretended to be sympathetic, but whined that they lacked "super powers." They refused to even try to contact someone at Inno who did have the authority to correct this. Worthless.
I'm still not happy about this. I've been a loyal player for five years or so. While I'm far from a "whale," I have spent several thousand dollars over the years. That's over; I'll still play, but I've removed my credit card info from Inno's files. It won't be going back.