Ethical Non-Monogamy

Hey all, I (26F) was having a conversation with a man that I’ve been seeing and we’ve had several conversations about non-monogamy. Primarily him expressing that men are biologically hardwired to sling d**k. Today we were having a conversation and he gave a hypothetical explaining that he prefers his women to be monogamous for him if he were to be involved with multiple women. Wife, mistress, etc.

The comment that I guess got to me was him saying that if he was apart from her (his mistress) for 2 weeks while with his wife he would leave to go spend time to keep his mistress happy so she wouldn’t feel neglected and be inclined to f**k other men.

Reality is that comes with non-monogamy, but am I irrational and delusional for that being off-putting? I get people want security and to indulge as well but I just don’t know how I would feel if I was married to someone, went through pregnancy and carried/birthed their children, kept their home in order, helped them with their entrepreneurial endeavors/business needs, and even financially contributed as well, etc. for them to tell me that they’re leaving for a couple weeks or so to go be with their girlfriend/mistress to keep them happy. I mean I guess it’s reality for most. Maybe I’m not looking at it objectively enough or maybe it’s egotistical and delusional on my end but I’m just wondering from other men, if I’m being irrational by thinking that a man saying and doing something like that may likely really bother me if I genuinely really loved my husband.