I'm unsure how you expect single people to form relationships , fall in love and get married. A you expecting arranged marriages?
For a few singleness is a calling, for most it is a stage of life which is passed through towards marriage.
In terms of whether or not I approve of dating, courtship or arranged marriages are not out of the question.
The point though is that the life of a single person is not the same as the life of a married person.
No one who is married can say they were not once single. But there are those of us who can say we have never been married. God has a purpose and plan for us, even if we stay single our entire lives. This would not involve relationships, falling in love, and getting married. Relationships, falling love, and getting married has to do with things like dating which are not Biblical. Those who are married can fall in love if they want. But I don't think they would think of it is a fall. Maybe spouses growing in their relationship with each other. Falling in love is simply a weird idea. People grow in their love toward each other in life, but there are different kinds of love. Some kinds of love are immoral. Some love is only for when you are married. And some love it doesn't matter who it is directed toward it is of God because it is in obedience to His commands, and not in disobedience to His commands.
Dating is like kind of being married without really being married. So, no sexual immorality. That is, dating does not mean sexual immorality. But it may mean unwanted emotional engagement. And, if any of this is unwanted, including dating people you are not married to or not engaged to or that just simply you don't know if you are going to marry them because you are not married (only when a person is married do they know they are married) then it just makes sense that dating someone you are not married to creates a situation where you may marry someone different if you want to get married, and that would be like adultery just that you weren't officially married to the person you were dating that you did not marry.
If you are engaged you can save yourself for your marriage. Being engaged is not permission to break God's law. Even if you think you know who you will marry you are still not to break God's law by not waiting until you are married. This may mean that an engaged couple will refrain from even dating, whether they refrains before they were engaged or not, in order to assure that they do not transgress God's law. Talking, discussing, and otherwise loving a person you are married to is not a sin.
Once a husband and wife are married, their relationship with each other excludes certain other relationships in the world that hopefully they have not previously had. That is, marriage is for husband and wife. And some things in marriage are for husband and wife and no one else.
Hebrews 13:4 NASB - 4 Marriage is to be held in honor among all, and the marriage bed is to be undefiled; for fornicators and adulterers God will judge.
