Legal Question in Family Law in Texas

Not unless you (a) had an agreement to be married - in the present tense, not in the future - or (b) you represented yourselves to others as being married ("Hello, I'd like you to meet my husband, Jeff") or incurred joint credit as "Mr. and Mrs." or filed a joint income tax return.

Merely living together does not create an informal marriage (often referred to as a common-law marriage).