Cats have feelings just like everyone else, excepts cats feel more entitled to getting what they want, more so than anyone else. This stubborn streak in a cat is what makes them so lovable.
Cats can experience jealousy any time their owner shifts attention away from the cat and towards something else such as a baby, another pet, or even another cat. To stop jealousy, spend quality time, one on one with your cat.
That’s pretty much what cats want from their owners anyway, 24 hours a day, 7 days a week, so as long as you cater to your cat, your cat will always be happy.