No point in preaching to the choir but fictional stories and all that.No he's partially right. Open marriages have a 38% higher chance of divorce and the couples involved have a 12% higher prevalence of mental health issues (compared to normal monogamous marriages). Opening a relationship gives ground to more lies and dishonesty, the only people who could benefit from that are cucks (people who get sexual satisfaction by watching their partner with someone else) or cheaters (people who get sexual satisfaction by cheating on their partner). In both cases, the partner in an open relationship plays the role of a kink enabler. And that's sad.
The point is to explore some fun kinky situations, not follow a blueprint for actual relationships. Perhaps even playing out fantasies you can't or wouldn't want to try in real life. Half the popular games out there have unrealistic harems too.
This is a happily-ever-after tale, however unconventional. A lot of the concerns raised seem to project personal insecurities, rather than considering the actual storyline and character dynamics being portrayed.