That title deserves careful thought as we seek a biblical answer: “Marriage should be honored by all, and the marriage bed kept pure, for God will judge the adulterer and all the sexually immoral” (Hebrews 13:4).
“Marriage should be honored by all.”—Even if your parents were bitterly divorced or you’d rather save for a beautiful wedding or marriage would cost you some social security benefits, God’s primary concern is that you honor marriage as God’s institution.
“And the married bed kept pure.”—God invented sex. He loves you and has put a sign on the bedroom door—Reserved for marriage.
“For God will judge the adulterer and all the sexually immoral.”—Sex before marriage is serious to God. If you stay sexually active without any remorse or repentance, God will judge you.
While I cannot find a passage that says, “Thou shalt not live together,” these words are my primary spiritual concern for every cohabiting couple. If you live together, you are likely to bring impurity into your bed and the judgment of God upon your head.
I know that means you might have a decision to make. Reach out to a pastor (I know that will feel awkward) and talk through your options. If he knows his Bible, he will respond to your repentance with Jesus, grace, wisdom, and a path forward. Will it be easy? No. Christianity rarely is. Will it be worth it to honor marriage? Your Father promises it. Trust him.