If someone suddenly placed me on this planet and explained to me the concept of marriage, I-me-myself (the Psych 101 dropout) would assume that OF COURSE! EVERYONE gets along with their in-laws! After all, these are the people who love the same person as you! These folks were the most important in your beloved's life prior to you! OF COURSE you would love them and get along swimmingly!
Or maybe this kind of thinking turns up the pressure and makes little differences feel like chasms.
One week down, one guest. One week to go, two more guests added tomorrow.