So how are all of your Lavellan's feeling about Solas breaking up with them and leaving?
I actually don't picture my Lavellan being angry at him, at least not for leaving her. She realizes that he didn't want to and clearly felt like he had to. She's more worried about him than anything, because whatever he plans on doing sounds really self-destructive and no good ever came out of a person thinking that they had to walk their path alone. If she's angry at him for anything, it's for not letting her try and help him. She's an optimistic sort so she's trying to ignore the idea that he's up to something that could hurt Thedas as she knows it.
Basically there'd be no yelling or punching if came back to her, though I understand those who feel their Lavellan would do that. 
Also, I love that Solas has some stubble going on! I wonder if there's any on his head or if it's completely smooth.
The breaking up isn't a huge problem. She'd be sad about that, but it's not a huge thing.
The leaving is what gets me. He just drops off the face of Thedas. Sure, he implies he might be leaving, but there's no "goodbye" no "there's something I need to take care of." Whatever his personal reasons are for not telling her, the fact is that the person she cared the most about and the person she thought cared about her (if not romantically, than as a friend) leaves her. And not like Leliana/Cassandra/Vivienne leaves if they become Divine; they have a purpose and a duty that Lavellan understands. Solas goes seemingly for no reason.
How she ultimately reacts...A lot depends on how he comes back and why. If he shows up again asking for her help using the mark I think she would be very hurt and angry, because she would interpret that to mean that he's only returning because she has something he wants. Double that anger if he doesn't bother to explain why he needs her help, but expects her to just trust him. Triple it if he keeps up the "we're just comrades" facade.
Then I have a headcanon where she starts meddling trying to find the creators, and long story short messes something up in a way that isn't really her fault. Solas finds her, angry that she did the "wrong" thing and she just explodes like "bro you lost your right to have an opinion when you left me."
But if he comes back for her? And it's clear it's for her and not for something she can do for him. Or even if he comes back because he needs her help but patiently explains what he's doing and doesn't leave her in the dark and tells her he loves her again?

Also want to share this fanart because I think it is pretty in-character but it's also NSFW (because topless Lavellan) so just a link: http://hawkeeffect.t...st/105466613901