Well I thought about why Ashley/Kaiden acted like a douche to you and i come up with a simple answer. Its all Human Nature people, think of the mind set they were in.
1st- They thought you have been dead for 2 years now
2nd- They find your working with Cerberus, an enemy of the Alliance so to speak.
3rd- They are human and they are Alliance soldiers.
If you factor all that in, it all comes down to trust. They thought you were dead and when they heard you were with Cerberus. That news didnt sit well with them and they jumped to conclusions. They thought you been alive the whole 2 years working with Cerberus and your death was a cover story(like some have said here). So you really need to earn their trust back, they are only human. Remember as human yourself, trust is something that can easily be lost but must always been earned.
I strongly believe your outcome of Mass Effect 2 depending if you favored the Alliance more than Cerberus on those certain missions when given a chance will result in them coming back in Mass Effect 3 on your side. Remember when you see them on Horizon, your only a traitor in their eyes.