The whole notion that manliness has to equate with controlling things and people, and being possessive of them to the point of jealousy is a bit silly to me.
It's perfectly fine to be jealous of one's significant other and/or not wanting to share their affection/time/body.
The reason for it can be a cultural taboo, a personal preference, an interpretation of mutual devotion, an insecurity, a reaction to past experiences or anything else. They're all valid reasons.
Making out that having a different disposition and being open to sharing means one is less manly or beta or whatever other label is in fashion this week, to me, simply means not having the life experience, knowledge/education or ability to discuss the topic.
The desire, or simple openness to share one's partner can have just as many reasons.. a personal kink, a thirst for new experiences, consideration for the desires and cravings of the partner, not caring for the partner enough to be jealous of her/him... Having a sex/porn addiction...
None of these have anything to do with one's "manliness" whatever that's supposed to be.
There are a bunch of couples and marriages that implode when the notion of opening it to third parties is explored. Most likely due to a lack of communication, consideration and/or clearly defined boundaries. In short, people who were not on the same page and weren't honest about it.
The people in couples that thrive and enjoy swinging or other non exclusive configurations, in my experience, are much more solid, much more in touch with eachother's emotions, much more confident of their partner's affection, love, devotion and integrity. They believe in their relationship enough to let each other play around outside its confines.
If anything, Zaton knows that in the end, his wife will always put him first, return to him and be devoted to him above all others, whether she occasionally has a fling with others or gets railed by another man/woman or not.
The same applies in the other direction. Zahra is a strong woman in her own right, who would not abide a man being unfaithful to her if she didn't know with absolute certainty that she's the first and last woman he will ever truly need, that he'll always come back to her and would die to protect her not just because hurting her is an affront towards himself but because he genuinely cares for her above all else.
Their relationship is their strength and it's so solid that they can indulge in whatever pleasure they pursue without shame or doubt. And it is true for both of them.
It may not be the most popular viewpoint, but to me that shows strength and confidence that's unmatched by most of the main characters in other harem games. A strength in relationship, devotion and mutual acknowledgement...
In most other games, the women are the only ones who bend over backwards for the main guy, who otherwise jumps between relationships with the permanence and truthfulness of a psychotic slot machine, effectively playing 5 different relationships in isolated boxes.
I like to think that whatever relationship Zaton pursues with other women, builds on the love story between him and Zahra, and isn't played out against it or despite of it, but rather feed one into the other.... And in that picture, I don't find it implausible that he might want to occasionally share the love or lust with others who are dear to him... Whether it's for his own pleasure/benefit or that of his loved ones.