You can't build a family if you don't have kids, and you can't have kids unless you have sex. When and if these two actually ever fornicate, Sumika will probably be past her child-bearing years.
end of chapter 31 and start of chapter 32 again, not really explicit but later on there is a better one, around 38 iirc since it was quite a while ago i read it
@FredFriendly let me humbly correct you:
You can't build a family if you don't have sex. Kids are irrelevant in this day and age, but (also, @kuma) statistics say that too much families fall apart because of dissatisfaction with sex life. @rymar
So, what is she going to build a family with? Cats? Dogs? Horses? Llamas? Kids may be irrelevant to you, but I'm 100% certain Sumika meant building a family with kids.
@FredFriendly
A husband and a wife is already a family, though (smart) people really underestimate that the need of having the children greatly outweighs arguments against not having them
Here in my country we just send a marriage invitation to literally everyone we know. Hell some people you barely know, and it's not uncommon to have 1000 guests.
The whole concept of sending people cards to inform them that you're married is very foreign to me lol.