Hm, this flies in stark contrast to what I've been told and what I believed, but you're right as far as I can tell, common law marriage does not apply if you simply live with someone for a long time.

For the record I had heard this from a lawyer, not some random person.

Depending on the state, you don't need to refer to each other as a spouse, just that people get the impression you're spouses.

My father's last "marriage" was like this. After several divorces he was dead set on never getting married again, made sure only his (or her) name was on any purchases, and made sure his friends knew the situation. After a messy breakup where he discovered she had been diverting money for drugs and hiding bills, her lawyer managed to convince an Alabama court to find a common law marriage. Not long after she ended going to prison for arson after setting aflame some of my father personal and real property in piques of spite. I think those felony convictions happened prior to or at least concurrent with the common law marriage proceedings.

All states in the U.S. that currently recognize or formerly recognized common law marriage require the couple to present themselves as a married couple, either by using the same last name, sharing bank account, or referring to each other as husband and wife, in addition to cohabitation.