The fastest way for you to lose your daughter, who, by the way, is no longer a “baby,” is by continuing to try to control her life. One would hope that, as a Christian, you hold among values most important to you and those that you instilled in your daughter treating others as you would hope to be treated, being forgiving, loving with an open heart, and being compassionate. I hope that you can embrace those values now, even if what is more important to you is the perception others have of you and your family. If you don’t embrace those values and if you continue to try to turn your daughter against her boyfriend in an effort to keep her from living with him, you will only alienate her and turn her against you, which has already started to happen.
Furthermore, maybe your daughter did pray about this, as you asked her to do, and thought about it, and then what felt right to her was to trust her boyfriend’s intentions and his love for her and to stay with him. Why are you so convinced that what is your desire for her is God’s will? Or, for that matter, her will? This is an 18-year-old young woman who has been with her boyfriend for two years, so why is it a surprise that she would trust his word over hearsay you picked up from who knows where, especially when you are obviously motivated to end the relationship before it moves to a step you are uncomfortable with?
You need to back off and let your daughter live her life. You don’t have to financially support her. You don’t have to pay for her phone and car. But, I promise you, if you emotionally cut her off because she has chosen to stay with a boyfriend she loves, you will likely lose her. And you’ll have yourself to blame.
If you have a relationship/dating question I can help answer, you can send me your letters at firstname.lastname@example.org.