Anime characters are no different in this regard, and their jealous feelings are born from both positive and negative traits. The best possible outcome for a jealous anime character is to learn from their passions and turn it into a character-building event. Meanwhile, some of them are jealous for comedy relief reasons. Regardless of why an anime character might be jealous, there are plenty who stick out.
He can't help but become frustrated when seeing families together, which leads him to aim for the role of Hokage, so no one can ignore him ever again. He also develops a bit of jealousy over others who are praised higher than he is, such as Sasuke Uchiha, who's a star student when he's not being a loner.
When Matsuri Mizusawa finds out Yuzu Aihara has fallen in love with Mei Aihara in Citrus, she takes it upon herself to break them up. Matsuri's predilection for shameless misbehavior stemmed from a lonely childhood where Yuzu was the one proverbial light she relied on to get through the day. Since she's so attached to Yuzu, she can't handle the idea of Yuzu being unavailable for her emotional needs. Matsuri takes it upon herself to stir up some drama to hopefully cause Yuzu and Mei to part ways, but it ultimately blows up in her face.
Despite its negative reputation, jealousy can be a useful feeling that sparks people to action. Depending on one's outlook, jealousy might inspire someone to take on more responsibility and better themselves spiritually. On the other hand, it might cause possessiveness and resentment.
Her desperation leaks out when she sees others in unfortunate circumstances, in which case she jealously looks on and comments that they seem to be having "fun." While Darkness's jealousy isn't expressed in a negative way, she's nevertheless envious of those who find themselves in embarrassing situations.
Specifically, Envy is resentful of the connections humans forge with each other since they never had strong connections of their own. Envy's ability to shapeshift into any form of their choosing is tied to the concept of envy and jealousy since Envy outwardly becomes another person. But the pit of hatred and loneliness inside them ultimately remains unfilled.
There's a lot for Inuyasha to be jealous over in Inuyasha, although his past doesn't excuse him for his rude, thoughtless behavior. Not only is Inuyasha jealous over humans and demons since each of them has a group they belong to that he's been outcasted from, but he's also jealous over others getting close to either Kikyo or Kagome. Since he's a character who's literally and figuratively stuck in between two different groups and circumstances, he can't help but feel resentment over nearly every circumstance in his life.