What happened between ME2 and ME3 that changed Ashley's attitude toward Shepard?
In ME2 she didn't even want to talk with you because you were with Cerberus. She acted like you just made the biggest act of treason ever.
In ME3 you start back with a her still a little mad, but in your party, and the relation starts back again.
So what happened that made her like Shepard again?
(except for Shepard leaving Cerberus)
Best Answer
Even after her angry reaction towards Shepard's decision to work with Cerberus, Ashley sends him a mail apologizing for her outburst. In part, it reads:
Even so, she gives Shepard a very hard time on Mars, and in several exchanges between them you can try to convince Ashley that you did what you did for the good of the galaxy.
Shepard's also returned to working for the Alliance, and has more or less severed ties with Cerberus. It's pretty clear by the end of the Mars mission that Shepard is not on the best of terms with them.
I think taken as a whole, it's not too farfetched to conclude that Ashley's concerns about Shepard's temporary alliance with Cerberus have been overshadowed by Shepard's continual struggle against the Reaper threat.