ANSWER:

If they commited zina, then they must first repent sincerely, cut all communications, wait until she gets her menses and then he can propose to her father and get married.

https://islamqa.info/en/answers/87894/he-wants-to-marry-a-girl-with-whom-he-had-a-relationship

Sheikh should a man marry the woman he is in a haram relationship in with if he loves her and she loves him but they started the wrong way and now want to do it the right way

Fiqh of Marriage, Pre-Marital Relations | March 24, 2019 7:46 am
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My bro in law wife wanted to learn Islamic course(WhatsApp,skype)the teacher is a lady.no video call is there.my BIL is not willing to make her study.is it compulsory to take his permission.