>>101946499I think it's upsetting because of the context and it certainly invokes much more pity and sympathy towards Donald that what it intended.
Donald is a very angry yet tough character so seeing him in that vulnerable state is quite sad. Genuine sadness and feelings of dejection are obvious, and it's really effective. He also seems betrayed in that Daisy, who is supposed to support and love him, pretty much instantly focuses her attention to something else when he is in need of someone to be by his side. And considering she is supposed to be his girlfriend and also is the one who initiates the talk, that just adds onto the pain, and not to mention humiliation (something which Donald is vehemently against enduring). And there's also the subtle innuendo at Daisy being more excited to see Mickey than she is to see her own boyfriend.
It's supposed to be a joke, but it comes off as mean-spirited and it would have been better if they actually had talked it out. It seems off, and Donald's reaction to it seems so genuinely hurt.
A little off topic, but I wanted to mention something important. Roger Rabbit. What made him such a great character is how he was portrayed, not just as a toon on stage, but also off-stage. Talking about things like being framed for murder, the infidelity of his wife and such topics made him so likable as he wasn't just always this whacky, zany toon. He showed he had feelings that people could relate to.
This scene, this 15 second long scene, is an important glimpse into that. A very brief look at Donald's off-stage personality. He's not being that angry, temperamental toon everyone identifies him as. He has self-esteem issues and he gets hurt and depressed like a person.
That's why that little gloomy duck face is making you sad anon.