i'm having a similar problem and i don't know why.
playing shattered lands i've only started 2 wars, 1 of which i had no cb for... but that was over 10 years ago in game time. since then i've captured scotland, ireland, wales, most of paris (barcelona got the rest) and some of belgium-lux (the country collapsed and merged with netherlands) after they each declared war on me.
now i'm stuck in a loop with everyone elses cb constantly going up and everyone taking turns to declare war on me. i've had to resort to using the mp save thing to get other nations to accept peace agreements. even tiny nations with maybe 30-40 outdated units under normal circumstances won't accept peace even with a few hundred billion of cash and resources thrown in. i sort out the wars and a year later they are all declaring war on me again.
i try and do research that the world is supportive of, that doesn't help. i tried building up my military up to around 400 hightech units as a deterent, but didn't have them near the borders and that didn't work. i also read military buildup can annoy countrys as it is taken as being aggressive - i reserved most of my military, left a few ships patrolling my waters and west germany still goes and declares war on me.
due to my relatively high gdp/c and not fully understanding supply yet my manufacturing prices for the most part are above market prices so automatic sales aren't happening although i make a lot through diplomacy.
two things tho - i have launched a few satellites, communication and recon, and do have a lot of military manufacturing facilities 30 ground, 14 air, 15 sea and 34 missile. i don't know if these are contributing, if they are can i get away with making them inactive or would i need to scrap some of them to stop people forever being annoyed with me?