Moving somebody into a home that you bought without them is a step that has to be made with care and consideration. Living with a romantic partner in any context is risky; if things go bad, there is every chance that one person will end up either without a roof over their heads or paying a significant expense. This is taken to the next level when you are the person who is ultimately responsible for the property.
The unfortunate truth is that a lot of us can't accurately guess what somebody is going to be like to live with until we actually do it. It can reveal a whole other side of a partner who seemed perfect until they started cohabiting with you. While it is only natural to have an opinion on how your living space should be, that is only justified insofar as you contribute to it. While some may resent being asked to contribute to somebody else's mortgage, a lot of people would expect nothing less when inviting somebody to live in their hard-earned home.