He's talking about how some "alpha/sigma" male types fear that women are after their money and worry about that (that's what I understand the grandparent to mean by "mercantile fears"), but (surprisingly to him) they don't fear that they will affect their psyche/personality.
A paradox which I don't think exists in the real world, as these types, absolutely do fear women will do that (e.g. they fear that women would effeminate them, or make them docile, or p...whip them, and so on).
You start dating someone, you become another person with different customs and passions. The more you invest in relation, the more is the difference, unless you had exactly the same prior background.