One thing that occurs to me: Are people experiencing a lot of wars inviting people to 'visit their capital' on first meeting? I learned to stop doing that, as that basically gives the AI a scout that tells it whether it's a good opportunity to attack - and since I no longer do that to adjacent civs, they don't seem to attack.
I'm in an interestingly unusual game at the moment, as Rome. My closest rival is Cleopatra, who needless to say dislikes me. I was prepared for early war but it never came - she did start amassing an army on my border at one point, but I had a walled and garrisoned city and was next to Singapore, one of my vassals and which had a reasonable army of its own. She turned right round and attacked an adjacent Hungarian city.
The Hungarians themselves were in a strange position - America had captured Buda, but the Hungarians seemed to be surviving well enough without it and had already founded several cities - America was too far away to overcome that loyalty pressure, and so currently Hungary has an independent capital that it doesn't seem to be rushing to take back, focusing more on the war with America.
For my part I declared war on Cleo - my intent had been to catch most of her army out of position and have it wiped out by Singapore, which had several adjacent units, ideally before it took Székesfehérvár (the city adjacent to Egypt and Singapore). I'd forgotten to denounce her and my own units weren't close enough for a surprise war, so she'd already taken the city by the time I was able to attack, and also saved most of her army. It did however trigger an emergency in mine and Mattias' favour, so I continued the war until I recaptured Székesfehérvár and got the reward (I gave it back to Hungary).
That left Egypt licking its wounds but having lost nothing significant (though I did capture a settler to replace one that had been wiped out by a volcano even while escorted - I didn't realise that could happen), a capable and competitive Hungary that has everything except its capital, still independent, and the ongoing America-Hungary war, all some time not far off turn 100.