Talking with a friend about the relationship dynamics between boyfriends and girlfriends

Friend born in 2002, found a girlfriend born in 1997, they’ve known each other for about a month. The girl wants to register the marriage, but the guy wants to take some more time to get used to each other.
Because of this issue, they keep arguing. The girl keeps bringing up the idea of registering the marriage, and the guy finally responds that he’s okay with registering but wants to do a health check and check the credit report first. The girl then explodes.
She asked me what to do. My friend still likes this girl quite a bit.
I told him that his idea is correct, but his way of expressing it was too blunt. The girl’s repeated insistence on registering the marriage is mainly because she lacks a sense of security. If he can give her enough security, things would be much better.
Is my advice correct? Are there any experts out there with some tips?