Is this natural?

[RomulusAugustusCaesar]

In my Makedonian game, Epeiros is waaaay too over confident. In an earlier game where I played as the Romani, once I conquered Taras the Epeirotes were only too happy to make peace with me. But in my Makedonian game, I have conquered Ambrakia, Epidamnos, and Dalminion, leaving Epeiros with just Taras and Rhegion, and they STILL won't make peace. I tried for peace when I took Ambrakia, but they refused, which is understandable. I tried again after taking Epidamnos, and they still refused. When I took Dalminion, I also killed Pyrrhos, and I thought to myself, surely they will surrender now. But no, they won't stop the war. Their army is depleted, but they won't give up. Why are they so warlike? Is it some kind of scripting to make them hate Makedonians extra?

[MarcusAureliusAntoninus]

The diplomacy in RTW is not very balanced. Once you have been at war with a faction for a couple years, they will never, ever, for any reason accept peace.

[Mouzafphaerre]

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Diplomacy is an unfeature in TotalWar games. Maybe I should put the longer explanation of this on my user page. It has some role playing value, though, and can be pretty much fun if you manage to restrain yourself from exploiting, using the Force Diplomacy minimod.
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[julius_caesar_the_first]

Is there anything that can make the diplomacy better (other than the force diplomacy mod)?

[mcantu]

Cant their attitude towards Mak be toned down in descr_strat?

[Tellos Athenaios]

Of course, it can, but the point of this attitude is to encourage Pyrrhos the *...* to actually attack and seize Pella for a chance.

[overweightninja]

Is there anything that can make the diplomacy better (other than the force diplomacy mod)?

I've heard lowering the campaign difficulty to Hard or Medium can help relax things a little, the military and diplomacy AI are apparently nothing to do with eachother though so I'm not sure how much difference it'll make to the diplomacy side of things.

Cant their attitude towards Mak be toned down in descr_strat?

The only thing I can think of would be changing the tags for factions reading things like "trader napoleon, balanced ceaser etc", I however have no idea how much of an effect if any these would have (never looked into what that actually do but I assume it's the "personality" of the AI).
Setting factions to be allies with eachother at the start of the game is possible and would probably help (for a limited amount of time anyway), however that would have to be something you take on yourself as I imagine the current diplomatic relations are designed to be historically accurate.

EDIT

Of course, it can, but the point of this attitude is to encourage Pyrrhos the *...* to actually attack and seize Pella for a chance.

Yes, the hellenes knocking the crap out of eachother is always the way to go :D

Cheers