I mean it is a crazy plot but ig it makes sense for the time it's roughly set in
Calling someone with endearing nicknames can also count as platonic! While yes, it is a weird for the ml to call him that but it seemed like the ml didn't find him romantically at first and the nn can also be a meaning of being loved and cherished whether platonically or not.
It is strange and concerning for us and we will never get it. But also for me, i find that it fleshes the setting and world building that the story is trying to materialize. Like its convincing that this is a different world with different culture and customs because it didnt shy away censoring topics that for them is normal, but not for us. Neways, as long as they didnt use those concerning themes to wrongly or abuse it. ╮(￣▽￣)╭
Im so glad they added a time skip and they're both adults now but...this is just romanticised child marriage. Why did he immediately call a 30yo man bride as a 10yo as soon as he saw him