make an honest woman (out) of
US /meɪk ən ˈɑnɪst ˈwʊmən aʊt əv/
UK /meɪk ən ˈɑnɪst ˈwʊmən aʊt əv/

1.
to marry a woman after having had a sexual relationship with her, especially if she is pregnant or if they have been living together for a long time without being married
:
•
After living together for years, he finally decided to make an honest woman out of her.
•
He felt it was his duty to make an honest woman of her after she became pregnant.