Responses
Right. Kotani might be operating on a "common law" marriage standard instead of the ceremony and legal portion of it. But my issue with him is that he thinks Shishikura wants the "party" of it. This omega dude has already accepted the idea of having a baby with him since the last book; he's ready to take all the nuclear family steps. I would find it very insulting if my partner said he would give me a wedding but have no meaning behind it.
Marriage ain't necessarily common where I'm from, you get together and last as long as you can and then split easy. My parents were never married but they were monogamous and lasted 14 years. Shishikura wants to get married and but Kotani doesn't, so it seems mismatched. No marriage is fine if both individuals don't want it but when one does? Problems. Kotani isn't wrong to not want marriage but he's wrong that they didn't talk about before hand (shishikura as well). Everyone shouldn't be so quick to call him trash, we don't know his reasoning yet. But he's probably end game anyways