2 things i do not understand

So after a couple a games in trinity I am quite pleased with all the changes, it made an awesome game even better,

the 2 things im about to name, are not meant to complain, mind you, they just make me wonder,

so for the first one,

In a rather large map i managed to be friends with everybody while they were busy hating each other, diplomatic heaven you could say, and before long, i managed a diplomatic victory, now what i do not understand is following, since i was busy with my diplomatic standings, my military sucked big time so when it would appear like i was gonna win why didn't one of my allies try to backstab me, after all, isn't the AI supose to try and win? Even though we were allies, allied victory was off so in the end they didn't even tried to win...

2nd one is a bit more simple,

multi-star map 5 vs 5, one star with 1 desert, 1 vulcanic, 2 astroids and 1 dead astroid, all mine and all with a bit of defenses nothing major, at this point, there are 3 enemy fleets kicking my ass on the dead astroid... using dark amada i try to fight back because they already destroyed my normal fleet, an ally tried to build a starbase (i cant since im trying the achievement to only research empire-things) succeeded and then got destroyed...

why on earth do they care for the dead astroid so much?? of all the targets... why that one?? they all are 1 phaselane from the star so distance doesn't matter either i asume