Hi all I'm new to this game...after beating an AI 1v1 I decided to play a 3-way free for all map

Was doing ok, I controlled 3 of the 9 planets so at the very least I was on equal footing with the AI, and I was able to easily repel individual assaults on my main forward planet.....and then both AI's ganged up on me and sent their fleets to hit the same planet at the same time...game over

This happened again when I restarted the game.....so it seems inevitable that I'm gonna get my butt kicked as the AI's clearly prefer to fight me instead of each other...any solutions?