Oh boy... it's a game.
There are no marriages in DA2. Except Sebastian, I guess, in very particular circumstances (I did that once, had fun). But the only thing that stung me in the Anders romance was that I couldn't support him more firmly, which I wanted to. I also think DA2 had the best characters and romances. But it's a game.
Otherwise, yeah, marriage. In DAI. I like the concept. I wish it was better executed, with the characters we got.
I'll try to get back on topic, as I derailed everything. Sorry.
I guess the point is that marriage is often seen, both in game and in real life, as the endgame of romances. Whether or not this is right, is, I guess, down to your prejudices. But I definitely wanted my Warden, Hawke and Inq to tie the knot with their partners.
If you want to compare the DA games, then you could definitely say that, marriage or no, the conclusion of romances, whether or not they run off into the sunset; or however else you want to define the conclusion of romances, Inquisition is the best.
I romanced Morrigan, then Merrill, then Cass.
I was disappointed that my Dwarf inq couldn't marry Big Cass, they were a cute couple and they would have just had the hairiest, muscle-iest babies. But at least they stayed together, and she was Divine, so that was that. It's as good an end to their romance as I could have expected, though a marriage option would have been nice, given that the Divine could always just change the rules (Andraste herself was married) and the proposal getting shot down kind of feels like a bait-and-switch.
When Morrigan left, I was genuinely surprised. I felt... bad for my warden (that's as good as I can describe how I felt) Then, during witch hunt, My warden left through the eluvian with her. But there wasn't really much follow up, we never got to see them together again, generally Witch hunt was disappointing, so as a payoff to a romance it wasn't great, despite Morrigan being IMO the best romance of the series and the most relevant one to the story. Compared to the beginning of DA2, where your sibling who you don't know or care about dies. Morrigan leaving is a lot better and the confrontation with her is what saves an otherwise very poor DLC episode. You get to know her, she becomes useful in a gameplay sense, you melt her icy exterior, then care about her, and then she betrays you and leaves, and Witch Hunt gives you a chance to confront her again, either for revenge or reconciliation. It's very cathartic, just like Trespasser, but way more vague and light in every other dimension.
It made no sense to me that Hawke and Merrill wouldn't stay together, although one thing I liked was Merrill's depression and her restlessness in the Hawke mansion. I liked that not everything was smooth sailing, but I didn't like that there was no way to really keep the two together. At least it made more sense for Merrill and Hawke to (kinda) break up, than it did for Hawke and Fenris, or Hawke and Isabela.
If you look at Solas compared to Anders, the Anders thing completely sideswiped me and it's clear that there is no way the Champion can maintain peace and stay by Anders. That romance is doomed, and it's doomed in one fell swoop by something I never saw coming. If I romanced Anders I'd have been annoyed that his (imo senseless) actions essentially rendered that romance dead. But Solas is genuinely kind of heartbreaking, and this is from someone who has only seen the romance cutscenes on youtube. I would feel immensely satisfied by that romance, even though it ends in heartbreak.
I guess my main point is, TLDR, it's an emotional storyline. What is important is how you feel, and Trespasser is definitely the most emotional, when it comes to romance, even if it gives a lot to some and little to others.