There are many instances of bridal abduction in Medieval Europe, especially to wealthy heiresses. In fact, marriage by abduction continued to occur in many areas well into the modern era, for example in Ireland as late as the late 18th century. In general, kidnapped women had very little recourse, a sad outcome that continues to be true in many places still practicing bridal kidnapping today.
That said, most marriages at any given time did not involve such objectionable conditions.
[A]bductions attracted attention often through the subsequent legal proceedings, but they were the exception rather than the rule. . . . In many cases . . . it is probable that the attraction of an heiress's or widow's land was more powerful than the personal factors. The girls and widows who were abducted mostly held widespread estates or had the prospect of inheriting considerable landed wealth.
Ward, Jennifer. English Noblewomen in the Later Middle Ages. Routledge, 2014.
Strictly technically speaking, bride kidnapping was not legal in most of Medieval Europe, under both secular and ecclesiastical law.
Subsequently, strict sanctions against abductions existed throughout Europe. Childebert II tried to impose death or exile as the punishment for the capture of a woman. The secular penalty was a stiff fine of fifty two and one half solidi, or the amount o the brideprice.
Gravdal, Kathryn. Ravishing Maidens: Writing rape in Medieval French Literature and Law. University of Pennsylvania Press, 1991.
The church likewise disapproved of the practice. As early as the Fourth Council of Orléans, the church has threatened non-consensual marriages with excommunication, although it was the consent of parents that was deemed important - not the victim-bride herself. The mentality of treating women as property whose value could be harmed through sexual crimes persisted, such that by the High Middle Ages:
The hierarchy of sexual crimes is clear, if complex: the abduction, with or without her consent, or a virgin, widow or nun represents the gravest crime of raptus; the defloration of virgins or widows outside the context of abduction and irrespective of consent is ranked next as stuprum; the rape of wives is placed lowest on the scale as fornication, since , in this case, sex, even if non-consensual, does not decrease the woman's value.
Saunders, Corinne J. Rape and Ravishment in the Literature of Medieval England. Boydell & Brewer, 2001.
In practice, legal detail didn't matter much, as they continue not to today in regions where bride kidnapping is still common. Cultural factors largely compel the victim to acquiesce to their fates.
Now for some specific examples.
One of the more tragic cases is Alice de Lacy, an heir to two earldoms. She was first abducted in 1317, despite still being married to Thomas, Earl of Lancaster, by men loyal to John de Warenne, Earl of Surrey. This was actually not a bridal kidnapping since Warenne ended up not marrying her, but after Thomas was executed as a traitor in 1322, much of Alice's lands were confiscated and given away - to Warenne's benefit. Alice then remarried to a household knight, Eubulus le Strange, apparently for love. After his death however, the then 54 year old Alice was abducted again by Hugh de Freyne. This time, she was forced to marry her captor.
Contemporaneous with Alice de Lacy were the de Clare sisters, Margaret, Eleanor, and Elizabeth. Their father Gilbert de Clare was one of the wealthiest men in Medieval England, so when his only son fell in battle without issue in 1314, the three sisters became co-heirs to his vast fortune. Unfortunately, this made them extremely coveted targets.
Elizabeth, was first married to John de Burgh, an heir to an Irish earldom. They had a son, but John died in 1313, and Elizabeth was recalled to England by her uncle the King. King Edward II probably hoped to arrange a marriage, but his plan hit a snag when Elizabeth was then abducted by minor Irish noble Theobald de Verdon. He might have known her in Ireland, but was 17 years Elizabeth's senior, and died shortly afterwards. Edward II then pressured a pregnant Elizabeth to marry Roger d'Amory, at the time his court favourite. Elizabeth widowed for a third time at only 26 years old when d'Armory lost favour and died in the Dispenser War.
Eleanor was married to Hugh Despenser the Younger, another favourite of Edward II. This marriage survived much longer than her unfortunate sister's, but in 1326 Edward II had Hugh hanged, drawn and quartered. William la Zouche, a baron who had helped captured Hugh, then abducted his widow Eleanor from her castle and married her.
Unlike her sisters, Margaret managed to survive these turmoil decades personally unscathed. She was married twice, first to Piers Gaveston and, after his death, to Hugh de Audley. With Hugh she had one daughter, also called Margaret. However, in 1334, the younger Margaret was abducted as a teen by Ralph de Stafford, a middle aged widower.