Marriages beginning without cohabitation according to this site last better:
Sociological Reasons Not to Live Together
We ought not settle for the unholiness of premarital sex, even if we are in that boat. We need to be sanctified and be free from bondage, rather than complacent and living with sin and filth. We need to repent and continue towards admiring Jesus. And His blood sanctifies and cleans and restores honour and the history of the body.
I think on the matter of history of the body, I would abstain form oral sex with a wife whose history was befouled. Foul mean the decomposition of Friendships, loves, esteems, sanctity, honours and other things in the history of the soul... What we do in our bodies and souls is in our history. It is in the body forever. It can be covered in Jesus' blood.
We from scripture, "hate even the clothing stained by sin." And are "like a firebrand snatched from the fire." The book of Ruth includes a part about the
kindness of abstaining from fornication. This very important because these two people Ruth and Boaz were Jesus' by Mary's ancestors. And the theme in all the Old Testament books was of the preciousness of the honour of being first love, as an analogy for worshipping God with no gods before Him.
Jesus heals sickness but His blood heals us from sin. Jesus' blood was poured out to clean our hearts from fornication and restore our honour and sanctity, separate soul ties. To warm hearts and fix damage to the human spirit. People who receive grace often prefer it to sin and drugs. We need that deeper grace that moves us to repent from the core. And Jesus' blood does not take things away from us.
It is not nice to think that someone else is becoming the first love of the young lady I'd like to marry, or otherwise.
If she says she does not regret it, or she loved him more, or he was better... these are hurdles to romance.