Didn't Anders and Fenris have some jealous bickery banter if you romanced both of them? I never did it but I think I saw a clip of it on YT or something.
Dorian is meant to be a bit bitchy so their could be some of that I guess.
(If Hawke spent the night with Fenris)
Anders: I can't imagine what Hawke sees in you.
Fenris: It is done. Leave it be.
Anders: Well, good. I always knew she/he had some sense.
Fenris: Do not make light of this. Leaving was the hardest thing I've ever done.
(If Isabela is in the party)
Isabela: Oh, will you two get over yourselves? You're like two dogs around a ****** in heat.
Fenris: We were talking about Hawke. Not you.
(If Isabela is in the party and you slept with her as well)
Isabela: Oh, will you two get over yourselves? I did her/him too.
───────
SourceI was so mad a Fenris - that
staying was the hardest thing he'd never done. I was so tempted not to finish his romance when it triggers in the third act, because he'd hurt my Hawke and there was no reason for her to be sitting around waiting for him. But I was glad I caved.
I would expect Dorian's eyes to get hard in jealousy but for him mostly to hold his tongue until he could speak to his Inquisitor alone; but of course - everyone has a boiling point and an outburst requiring later comfort would be satisfactory too.