Fornication occurs regardless of whether or not love is present.
And yet you do not address any of the passages of Scripture I gave. Let me tell you my story.
When my wife and I met, through a mutual acquaintance at church, we became friends and started dating within a few weeks. A week after we started dating, we discussed where we both thought it was heading, which was marriage. So, yes, we could not stand being apart either and spent all the time we could together. But we did not move in together nor sleep together prior to marriage because that is what the Bible calls fornication.
Being in love is irrelevant as to whether or not fornication is a sin. And, yes, having that piece of paper is just a legal thing and irrelevant as far as the Bible is concerned, but that is not a biblical argument. Marriage is a vow, a covenant before God, and most importantly, a metaphor for Christ and the Church. As Deuteronomy shows, to sleep with a woman outside of marriage was to violate her.
A Christ centred relationship puts God and the Bible first, not one's desires. Anything else is a self-centred relationship. It is worldly thinking to believe that as long as a relationship is based on "love" and doesn't hurt anyone, it's okay.