There is a large Romani Community in New Jersey, USA, especially in the Garfield area, and, while I don't know how this tradition functions in Europe, in New Jersey, it is little more then a theatrical tradition CONSENSUALLY engaged in by all parties involved. The 'kidnapping' is carried out by a couple that is already engaged, three days prior to the wedding, as part of the kidding tradition, not as an actual 'kidnapping'.
I even witnessed one such 'kidnapping' and found it (very) humorous. Specifically, the "kidnapping" took place at the brides parents house, who were my neighbors, because tradition demanded that she be 'kidnapped' from her parents house, in spite of the fact that she had her own apartment*. The groom-to-be attempted to carry his fianc out of the house, but couldn't lift her and, after nearly dropping her, she made a theatrical display of pretending to struggle as he led her by the had to his car. She then sat, peacefully, in the car until he got in the drivers side and she resumed her "struggle" to escape.
The whole time, her parents engaged in a comical slow-motion chase of the couple.
Then as he "sped off" (aka. chirped the tires) her parents and other gather relative cheered.
The wedding was three days latter.
In short, at least in New Jersey, the tradition of 'Bridal Kidnapping' has evolved into a harmless tradition practiced by Romani couples with the FULL CONSENT of all involved... To be CLEAR, it was obvious from her deliberate over-acting, the presence of her family (who were also over-action) and the fact that she was willingly walking off with him while pretending to 'struggle' that this was a staged tradition, not an actual 'abduction'. Furthermore, he parents told my neighbors and I to expect this (so that we wouldn't call the police or shoot the husband/fake abductor).
*She was only staying at her parents house as a way to keep with this tradition and was therefore a willing and informed participant.