Excellent companion reading: _The Gentleman in Trollope: Individuality and Moral Conduct_ by S. A. Letwin. A fine tour of Trollope's novels, but also a deep reflection on what gentlemanliness really means. The author, iirc, concludes that Madame Max is the most perfect gentleman in all of Trollope :-)
But I agree, in the present age we seem to be enthralled by rudeness and cruelty. "Behaving like a gentleman" doesn't always mean you're a wonderful person (it's possible to cut someone dead with the most perfectly civil manners, and to be an impeccably gracious host while exploiting your servant labour) but taking the basic principles to heart--honour, loyalty, kindness, modesty, graciousness, self-discipline--certainly seems like a good step on the way to better-person-hood.
One mark of "a true gentleman" in the really old days (when "gentleman" meant someone from a propertied family who had been properly educated) was this: a real gentleman is particularly careful to be courteous to those who are subject to his power or social advantage. He is polite and considerate towards his servants, taxi drivers, waiters, and all the rest of the "underclass".
The reason: it is ungentlemanly to take unfair advantage. The servant class had no recourse, was not allowed to talk back or show their feelings, so they were sitting ducks for displays of bad temper or abuse from their masters. The real gent (while of course never questioning the system that put him in that powerful position!) would not abuse his position to bully or insult a helpless person, any more than he would hit a boxing opponent below the belt, strike a woman, or "hit a man when he was down."
This all seems a bit precious to some of us today, but the basic message is still important: it's about not abusing one's privilege -- being conscious of it, and exercising restraint. Those of us who make better than minimum wage would do well to remember this when interacting with the millions who barely make minimum wage. Maybe we can't reduce the insane, historic inequity of the wage scale tomorrow (though it's worth working towards that end, imho), but we can be polite to people in service jobs, and refrain from using our relative wealth advantage to bully people who are systemically unable to "hit back." Same goes of course for race, gender, age, etc.
Men and women alike could do worse than to aspire to be the Perfect Gentleman. I can't claim credit for this quip, and can't even remember where I read it, but some witty woman or other once remarked, "My dear, I always try to behave like a lady... AND a gentleman."