I'm playing vanilla so don't have grievances per se, but it does seem like warmongering is punished a tad too heavily. It feels like if I ever declare a war, or if I ever capture a city (even if they started it) it becomes close to impossible to ever get into people's good books again. They keep denouncing me and even declaring war on me for my warmongering, causing a viscious cycle; they denounce me, get mad enough to declare war on me, I defend myself plus try to knock them out of the war so I can have a bit of peace, we declare peace, they get upset at me because I'm a warmonger...
I mean, sheesh, yeah I did declare war on some random guy to grab a city that was blocking any hopes of my Civ expanding, but that was 2,000 years ago now...and did I mention that the reason he's no longer around is because you killed him off?
It's a bit frustrating also because in real life even warmongering states can get allies. Eg the US has been at war for most of its existence (if you count the undeclared wars as welll) yet it has plenty of allies. This isn't meant to be a discussion about the US but if I did that in Civ I'd be lucky if I had one ally; that's only if i haven't knocked Alexander out...