Ross is a mixture of Insufferable Genius and Honor Before Reason, but you wouldn't see why until you looked at him this way; Monica had to grow up always being The Unfavorite while Ross was the star child of the family and because of this, Ross was always praised for every single thing that he did while growing up and should Ross ever get into trouble, it would be safe to assume that his parents would do everything they could to quite the mess so that Ross still comes out looking good. This leads to the present day Ross always trying to prove to his friends how he is right (whether it's on dinosaurs, who did wrong in a relationship, etc.) and how nothing is ever his fault. A good example of this is "The One With All the Secrets" where Monica told her parents Ross smoked pot in college (because Ross refused to admit it and had put the blame on Chandler back then).
- Adding to that, this troper found it odd that Ross and Rachel, who were both adored when they were growing up, failed to establish a steady romantic relationship but Monica and Chandler, who had a lot more emotional baggage, succeeded. Then I realized that was the point. Ross and Rachel were both extremely spoilt, Ross as the previously mentioned 'star child' and Rachel as her daddy's darling. Consequently they were both self-centred and egotistical which caused problems romantically. Monica and Chandler however grew up fighting for love: Monica suffering her mother's criticism's and Chandler being neglected during his parents divorce. So when they established a loving relationship it was extremely precious to them. They worked harder to hold onto it than Ross and Rachel who had always received support and attention.
- Monica always aims to please people, which probably stems from her not getting the same kind of love and attention that her parents gave to Ross. Monica brags about how she always had tea parties and baked for friends and how people liked her because of it. Monica also got into the culinary industry knowing that people will always try her food and compliment her for it. Whenever Monica gets dethroned as the best hostesses or anything else of the sort, Monica gets upset because now people will go to someone else and like them over her. This is also reflected when Monica sings at a bar and even after Chandler tells her that her nipples are seen through her shirt, she keeps singing anyway because people like her.
- It's acknowledged in-universe that both Chandler and Monica try to please people because of their unhappy childhoods. They even tease each other about it in one episode.
Chandler: "Is that the reason you became a chef? So people would like you?"
Monica: "You really want to talking about making people like you, funnyman?"