Consider a contract. When married people split up, they have a ready-made legal instrument, the divorce proceeding, to help them keep some or all of their assets. Unmarried couples don't have the same protection. Consider drawing up a written agreement about your finances, property you owned before you started living together and property you bought or inherited during your relationship. Remain financially independent.
Financial advisers recommend that unmarried people maintain separate credit cards and bank accounts.
Meanwhile, they say it's usually not a problem to have a joint checking account for basic household expenses. Be wary about co-signing. Avoid co-signing a loan or applying for a joint credit card unless you're prepared to assume full responsibility for that debt. Watch those titles. If you want your real estate or other property to go to your partner after your death, you can title assets jointly with rights of survivorship.