Okay, this game is definitely making fun of me.
Started a new game with 1.009, with Acutians as starting race. Flew around doing my Hydral thing, including setting up the race relations buildings so I could get the mutual +300 necessary to form the Federation (I eventually settled on starting with the Andors, Peltians and Evucks).
Meanwhile the Acutians, despite their poor homeworld conditions, were able to expand aggressively, overrunning the Burlusts, Thoraxians and Boarines. It was only after they had done this and formed a Fear Empire, however, that I had realized I had to stop them, and while I was repairing my ship after "dying" in a battle, they whacked the Andors as well. Then they went after the Skylaxians.
I was able to help repulse the invasion, and the surviving races began counterattacking:
At this point I was still 100-200 relationship points away from the closest viable Federation founding partnership (Peltian-Evuck):
Just one year later, this happened:
That's right. The Evucks and Peltians took one Acutian planet each, and since I had conveniently built up their relationship for them they decided to form a Solar Axis Pact together. And the only way to break it up is to undo all the work I did bringing them together for the Federation in the first place. FML.
God help me if the Skylaxians take an Acutian planet as well and decide to join the SAP too. Game over!
...So, I guess, what I'm saying is, +300 mutual relationship to form starting federation is really stiff. It could stand to be a lot lower than that. Especially when Create Federation for Safety/Create Strong Federation only need +90. Lower it pleaaaaase.