I had a special case in a recent game.
I was a bit behind everyone, and they all (except 2 that disappeared due to the foundamentalitst) got allied (i've never seen it before): alexians, carinoids, drengin, altarian, arcean. Each one allied with everyone else. Except me, allied with noone, and thus in not a very good position..
I that game I had decided not to get allies in order to avoid the multiple wars that never end (peace with an ally but not the other, so back to war next turn --- at least that was my experience until then).
At some point I tried to ally myself with some of them (Cari & Altarians), and did so.
But then the Drengin declared war on me, and everyone broke alliance with me. I destroyed some enemy ships in sectors where I had the advantage, and made peace with some of the aliens. For a few turns they remain in peace with me, then got dragged back to war. I choose the weakest civs and attacked them first, while defending against the drengin fleet (main power). After I gave the "little ones" a bloody nose, I made peace again. Then, next turn, offer them some money. And then techs. And send all my trade routes to them. At that point, with no trade and expenses at 100%, my income was -2000 a month (so after one year of war, I could only maintain that for another year). Suddenly the turn after I was close to both of them, so I proposed an alliance and surprise: something never had happened before happened. In the turn after that, they switched sides, and entered the war with me against teh Drengin!
And they were right to do so: Since I was defending only, in sectors with one maxed out attack & defense starbase
Usually I'm always the one left behind, even when I was first to make an alliance with a given race. They would always turn on me. Not always anymore it would seem
Since I saw that, I'm a lot more patient with the other shortcomings in diplomacy (IMHO).
Anyway, in the end, I invaded them all. So maybe they're wrong to give up on the Drengin...
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