For one thing, very, very, very few cultures allowed the couple to meet, decide to marry, and do it. And the alternative is not an arranged marriage where the bride and bridegroom have no say. I saw a movie taking place in (allegedly) ancien regime France, where a young man was in love, and so he was going off to ask the girl to marry him, and his father sent him off with his mother's ring. Not going to happen. Assuming you wanted to do something so scandalous as marry for love (and there was a scandal in ancien regime France about a couple who fell in love after they married, but then, love is blind), what he would have done is go to his father, and plead his case. Given that his father was agreeable, what would happen next is that the father would go to the girl's father and say I think our two young folks would make a suitable match, they would duke out the financial stuff -- and the financial stuff gets very short shrift from many writers -- and then they can bring off the match.
There are, after all, bridges between arranged matches and freely chosen marriages. There are those initiated by the parents or other matchmakers: the couple are brought together, after a thorough vetting, with the understanding that they could be a suitable match, all the way to the Victorian hostess who carefully ensured that everyone had been properly introduced and so vetted, so that the young unmarried women could wander in the ball and party knowing the men had been pre-screened.
And there are those initiated by the youngsters. They meet someone at a festival or at a friend's house, and the prospective bride(groom) is carefully displayed before both sets of parents, who can still give or withhold consent. It might be a legal or cultural requirement, or something where a failure means financial disaster. The threat to "cut off without a shilling" probably brought as much compliance as legal requirements.
Parents would carefully explain that love was all very well but marriage had to be about more important things. That is, if they thought that highly of marriage. They might say that dragging erotic love into was profaning the holy sacrament by misusing -- or a cultural equivalent. And the money would be thrashed out. Thoroughly. The bridegroom might stand for himself, particularly if he were an orphan, but the bride needed someone to handle those matters.
Then you get to the ceremony itself. Which is usually Crystal Dragon Jesus. Vows are a Christian invention. And not an early one. In the earlier Middle Ages, the wedding ceremonies, for those rich enough to have them, were the reading of the wedding arrangement where all the money was thrashed out, and the bride being (rowdily) escorted to bed -- which did not have to occur immediately one after the other. The vows were introduced as part of the fight over control of marriage. Whether men could dismiss their wives for infidelity, whether men could marry off their daughters without their consent -- the Church declared that the sacrament did not join families but united wills, and those who actually willed the marriage (the bride and bridegroom) had to make the marriage with their vows. A priest was not necessary, not until the Council of Trent -- and then he was introduced as a witness. (In fact, to this day, you can sometimes marry validly in the Catholic Church without a priest.)
So even in pseudo-medieval cultures, there's plenty of flexibility. And in others -- in China, a wife became a wife by being enrolled in the family book. It was considered commendably frugal for a widower to promote his concubine to second wife without any festivities at all. And we know little of Norse marriage ceremonies except that a hammer was involved. Once, the gods trick the giants by sending Thor to them, disguised as Freya, until they brought out Thor's stolen hammer for the wedding ceremony.
There's a lot of possibilities out there.