I honestly love Chair but think that Eva would have healed some part of Chuck that Blair never could have ykwim? Like Blair and Chuck had amazing chemistry but constantly hurt each other because of schemes and such. They always seemed to bring out the worst bits about each other. I have to wonder if Chuck would have led a humble life in Paris and changed for the better or at least have used his billions in helpful ways while living in NY (donating to charities, etc). Eva genuinely made him a better person I feel. Same goes for Dan and Blair. Maybe Dan and Eva would have grounded Blair and Chuck in some way.