Are there really no laws in MO about unmarried couples like she said? Or if there ARE, what are they? Am I not the Aunt of the children on his side?

Are there any laws about unmarried couples in the state of MO? At first, the woman I used to consider as my mother-in-law, said she looked up state laws. She said that it''s 7 years the unmarried couple has to be together, living in the same state w/o separating during the 7 yrs. Then, she said the state of MO doesn''t recognize domestic partnerships as legal anyway, regardless of how long they''ve been together. I''ve been with David for 6 yrs. During that time we have been separated 3 times. The 1st was for 18 months, the 2nd for 12 months, & the 3rd was for 5.