By medieval theory, they did not make arranged marriages. Marriages were contracted only by consent. Well, basically.
There are many reasons to consent. Some girls consented to marriage after being locked in their rooms for six months. Some girls consented to marrying their father’s creditor to save the family farm. Some men consented to marry a girl on threat of being fired and blackballed from further work in their trade if they didn’t (what we might call a “crossbow wedding”). But consent they did.
Unlike societies that considered it unseemly for a girl to meet her husband before the wedding, the Middle Ages believed in courtship. In courtship, the man brought the girl gifts and tried to make himself likable. Even before the 14th century’s fashion of romantic love, they considered it a very good thing if the couple actually liked each other. They believed in love, even if it was a practical daily kind of love. By the late Middle Ages, the diaspora-scattering of Provencal troubadours informed young ladies of status that love was only real if it carried no obligation. Although the songs praised adultery, the main popular effect was to raise expectations about courtship.
Promising to marry someone should be formal and notarized, and especially in Italy, where Roman notary customs had continued, it generally was. But verbal agreements counted too, and many court rolls tell us of disputes in which witnesses were called to say whether they had heard Richard ask Joan to live with him, and whether they understood him to mean marriage, and had she accepted a gift from him in token of acceptance? In most cases, it meant that Richard had decided that Mary had more money, and Joan was devastated. His words may only have meant seduction in a tavern, but if she could get some witnesses to back up her claims, Richard might find his proposed new marriage (to Mary) invalidated.
For this reason, the first step in planning a wedding was to publish the intention to marry. In archaic English, this was called publishing the “banns.” At least two Sundays before the wedding, the announcement of intention had to be made publicly in church. This gave Joan full notice and time to find her witnesses, to stop Richard from marrying Mary. Would she then marry the bastard herself? Abso-lute-ly. She probably couldn’t afford to take idealistic love *that* seriously.