I had many, many friends who moved this quickly during courtship, too.
I know that sounds cold but if you train under stress for that many years and become a member of a masochistic not the sexual context fraternity like macau dating service of surgical residents, then you more easily shut out anything that might break down those walls.
Edit - I just read through some of your other comments.
They could fill a rexdy, the stories I could tell.
Also, I'm having a really hard time understanding from these responses how anyone in the medical field ever dates or gets married.