What kind of professional should I speak to regarding protecting a house from auto defacto?

I am currently building a house for myself. My partner is moving in with me; first into a rental property, then once the house is built we will move into the house together. I have read a lot of horror stories of assets being automatically acquired in the case that you and a partner automatically become defacto after a period of time. i.e. In a worst case, that they are entitled to half the build in the event of a breakup.

Looking to speak to someone (probably a law professional) to discuss what I can do to best protect myself in this scenario. I mean I view it as I love her, she loves me, and neither of us would do anything to hurt the other or try to take advantage. However I can’t be certain that the version of her which "theoretically" no longer loved me would do. After so many years squirelling away funds, I am not prepared to risk my property.

What kind of professional should I speak to as to the best way to set this up to protect my asset?

Does anyone have any suggestions on what sort of terms and arrangements I can look into for this sort of scenario (surely it’s not an uncommon thing)?