Nothing in common? Not 100% true. Depends upon what.
For me and my wife, we can talk about daily events, news, our children, household decisions and family plans fine. Actually well.
Yet, what news events mean to society/the world do not create satisfying talks. How to educate and how/why to bring up our children...what things mean...are difficult topics.
Money? I avoid this one now. Hopeless.
In general....we are good housemates. Do our best in co-parenting.