It's easy to say that, not so easy when you're the person who thinks that someone you love might get hurt over you. Besides, Lavellan might agree to help but she wouldn't really have an idea of what she's getting into even if he tried to explain it, I imagine. What Solas is trying to do seems like it's on a whole other level than what we've dealt with before. We as a player probably wouldn't see it as all that mind-breaking but we have the player knowledge!
Letting someone make a decision that might be their death would be an incredibly difficult thing to do. I can't pretend that I wouldn't do exactly as Solas did and just walk away, or at least be really, really tempted to.
Bolded part: This is why I say it is selfish. Basically, as the person doing the breaking up, you are only considering your own hurt. If they decide to risk their life for you, that's their choice. What makes this trope so annoying to me is people think this is selfless, because wow it must suck to break up with someone you love (ignoring the fact that you just broke their heart too)! But you're doing it to protect them, so the end justifies the means!
I'm sorry, no it doesn't. Real relationships have a foundation of respect in them, and if you don't respect someone enough to let them make their own choice, then you are being selfish. Leaving someone to protect them is more about protecting yourself from the hurt of losing them if they died, or the guilt if they got hurt because of you. Notice every time this trope comes up they always say (or think) something along the lines of "I couldn't live with myself if something happened to you". Proof: It's your pain you're trying to avoid, not theirs, no matter how much you tell yourself otherwise.
Sorry I probably sound really angry but this is such a sore point for me. I'm all about freedom, choice, and knowledge, so the idea of someone making choices for me by denying me knowledge just make me grrrrr.
Now I'm not denying that it is a hard thing to do! I agree with you there. Letting someone risk themselves for you is incredibly hard. Which is what I mean when I say the trope annoys me: it's a copout. It's the coward's way out, not bravery or selflessness as it's often made out to be.