Solas is also someone who cares deeply but doesn't always show it openly, or can't quite do so. He has such deep scars and regrets and pain and from his speaking via Cole at the end, it seems like he feels like he's on some sort of suicide mission that he feels he has to do alone, in spite of his greatest fear.
All the feels, truly. I love and hate how obscure it all is, because we truly have no idea what they have planned other than the tiniest strands of speculation, mostly based on his past and other hints.
Oh the obscurity of it gets to me as well. I mean we literately have no concrete idea about what happened. Mythal/Flemmeth go on about something happening that was not suppose to happen. Solas drops countless hints and innuendo that the Elvhen "gods" might not have been that great after all. (I am seriously getting a Grecro/Roman vibe from them but that's just where I am at in my own speculation right now). We know that Tevinter was not responsible for the fall of Arlathan, but we are seriously shy on the details of what exactly happened.
On the note that there are a lot subtle things going on with Solas, I can't quiet shake the look he give the Herald once they get to Skyhold.
It starts around marker 1:23 and runs to 1:30, and I get chills every time I see it, because it strikes me as being a bit sinister or maybe calculating on his part, given that Skyhold is built on Elvhen the ruins that may or may not be associated with Fen'Harel. I really doubt that it is a coincidence that Solas knows where that keep was.
I do think he's someone who cares deeply, and I don't deny that he love Lavellan, she is his vhenan after all. I do not see him as someone who would use those words causally. But those feelings are not enough, at least at this point in the story, to stop him from doing whatever it is he's going to do, which I think could put our Inquisitor in danger in the near future. I am kinda afraid, as much as I love his romance arch, that there is a part of him that we've only caught glimpses of, ie All New, Faded for Her, that would not hesitate to use or break his vhenan if it furthered his end goal. I think that may factor into why he leaves so suddenly, he knows what he's capable of doing to her and himself to fix whatever went wrong. I know this is all very dark and twisty.