Loss of Influence when an Ally attacks?

i am playing as Scipii (med/hard) and what happens at arounds 170 BC? My erstwhile allies The Egyptians (maybe nervous of my African gains-i hold all Africa west of Egypt) attack.

Now do they get a significant Influence loss for their perfidy or do i just have to take it?

How do i gaurd against this sort of thing happening again?

From what I have read, if you did the same thing it would be harder for you to get other factions to ally (or believe you generally) with you after the event...

I have had the same thing happen to me in my new Scipii campaign just before I finished playing last night, so I shall examine the web of alliances to see if there are any other reasons...