So as long as the people involved aren't paragons of goodness and they love each other,abusive and unhealthy relationships are OK?
Paragons of goodness? Seriously is this your response? Because what you are trying to say with this implication does not counter my point. That two people who are this fundamentally abusive and unhealthy simply can't get into a better relationship. So the answer is they get with people like themselves (in this case each other) where they know what they are getting into and can handle it, get into a relationship with a person who can't handle the potential abuse here, or forswear relationships entirely.
The third is absurd, people don't do that. The second would be terrible and screw up someone who doesn't deserve it nor handle it. The first, as is the case with them together, is the best case scenario. Not to mention, for the first time they can approach each other on an equal footing giving more opportunity plus all of the lies are out of the way, so their relationship has the opportunity to turn healthy. Doubtful, but its far more likely with each other than either of them ending up with someone else.
Mmm, it's a little more complex than that. When Celene ordered Gaspard to offer his plume to Teagan for the play duel, many Chevaliers interpreted that as making a joke of their order while offering a curtsy to Ferelden. This curtsy to the "dog-lords" also managed to ****** off some of those among the general nobility who were still mad about the failed occupation.
I am aware. The thing though, is that Gaspard's insult had everything to do with the war. The silliness with the feather duel was not close to as horrible as his insult towards Moira's memory. Just the rumor of such a thing in Ferelden would have been disastrous for relations between the two countries, especially since they not only killed her but used her head as decoration above the palace gates in Denerim. The public slapdown was necessary not only to stop Teagan from doing something immediately disastrous, but going back to Ferelden afterwards with reports that would spoil relations between them.
We all make mistakes. I'm willing to give them another chance in a world where Gaspard isn't breathing down their necks.
You forget one thing. In the end of Masked Empire, after everything was sorted out, Briala outright admitted she would forgive Celene. The only question was basically if Celene would be similarly devoted after what Briala cost her there. The Behind the Empress quest shows that she will. Twenty years of a successful relationship is a lot of history and a lot of weight that can overcome even horrible issues. They had been together long enough that their goals very much align with one another and both want to support the other's. They clearly still feel for each other and would rather not throw away the twenty years together, and they have a lot of common ground now to build on as they work towards a common goal somewhat as equals. They have a chance to make it successful.