out of wedlock
outside marriage

Her brother killed her mother, because he believed she was seeing someone outside marriage.

Fred is apparently born outside marriage, not knowing who his father was.

Thirty years ago having a child outside marriage wasn't considered to be the accepted thing.

Children born outside marriage have become more common, and in some countries, the majority.

She had at least one additional child outside marriage.

But on average, Americans now spend half their adult lives outside marriage.

Any kind of sexual activity outside marriage is illegal in Yemen.

Most children were born outside marriage and therefore registered under their mother's name.

Sage was known to have affairs outside marriage both before and after the death of his first wife.