We've had a few conversations about how the choices in that convo are woefully lacking and a bit messed-up >< I actually had a conversation with my husband in which he was a bit amused with me because irl I often TOTALLY miss subtext with people and generally need things explicitly expressed. But he explained it this way; the whole conversation wasn't really about Dorian wanting to leave or even about him really wanting go back and reform Tevinter. The conversation was really about Dorian wanting to be reassured his place in the Inquisition is an important one and that the Inquisitor really does want him him there. But because he's who he is he can't just come out and say any of that so he does this whole "maybe I should go back home" thing to see what you say.
To me that makes a whole lot of sense, and it also makes a ton of sense why Dorian reacts the way he does when you say you need him there. He says saying the emotional blackmail thing was just a joke, and after thinking of it in this way I think it was actually.
I don't know. I'm also really bad at spotting subtext in real life with real people, but am pretty good at spotting it in fiction. I've watched that conversation a few times and I didn't really get the impression that Dorian is just fishing for conviction. That he's just saying that because he's passive-aggressively trying to get you to say, "No, Dorian! Don't leave! I love you, I need you! Stay with me!"
I got the impression that Dorian is, indeed, conflicted. He loves his homeland, but he also loves you. He wants to go home, but he also wants to stay. He wants to help reform his homeland, but he also wants to stay with his beloved. He wants to help you save and improve Southern Thedas with the Inquisition, but on some level I think he also wants to strike out on his own and make his own changes in the world rather than hanging off your arm. I think, on some level, Dorian feels ashamed of himself for running away from the problems in his homeland rather than facing them and trying to fix them.
Granted, he saw a much greater problem down South and came to fix that too (stop the Venitori, stop the Elder One, save Thedas), but I got the impression while talking with him about his homeland that on some level he feels he can do more, and eventually feels inspired by what you've been doing. You, the Inquisitor, saw great problems in Southern Thedas (mage/Templar War, Breach, Venatori infiltration, the Elder One, Orlesian Civil War, Demon Army, etc) and went out and did something about it. He probably feels, that he can do something about it too. But on the other hand, he is happy here (if restless) and loves you too, and on some level doesn't want to leave. Others have mentioned though that he's rather insecure in love and might be afraid to leave lest the relationship dissolve.
It seems to me like he really doesn't fully know what to do, and is looking for you to tip the balance one way or another.
That said, I have to agree with Fredward about this one. One shouldn't have to choose between "love" and pursuing their life's goal. It's like making someone choose between an education/career and marriage. It makes me really uncomfortable to say, "No! Don't pursue your own goals, hopes, dreams, ambitions, or self-actualization! Stay here with ME!" That can only work for so long anyway. Eventually "love" and the relationship won't be enough, and he'll come to resent you and/or the relationship because it's keeping him from doing the things he feels he has to do.