This has really crossed over into the usual isekai-style harem where all members love the MC but know next to nothing about them nor do they understand them in anyway. Like its pretty obvious the Snow Queen's plan wouldn't work with even the most cursory reading of the MC's personality. Hell how would he even find out about it. Every place in the world visited by the Hero and MC is seemingly facing problems right now that Univas is totally unaware of. Unless literally every place is somehow information isolated, this means Univas couldn't give enough of a shit about any of these spirits to try to keep tabs on them.
Univas apparently plans to marry all of these women, that's why he's been shown to care for them no more than random strangers. I don't remember or care to remember what the current marriage system is or why it's bad. I'll take his word that it sucks and needs reform. Needing the Goddess's permission for it is really stupid because if they signed off on the shitty system then they don't give a shit about Spirits.