February 29 is believed to be when woman have the chance to take charge and propose to men.
The British singer welcomed the fan, who had already proposed to her boyfriend earlier in the day, to the Belfast Arena stage.
The woman's boyfriend initially answered "maybe in a little while", but Adele wasn't quite happy with that. "You need to say a proper yes love... you have to say yes," Adele said on stage directed at the woman's partner Neil.
Adele encouraged the audience to get involved prompting the chant: "After three everyone say `come on Neil'".
The man replied with an exaggerated head nod leading Adele to dance in celebration before giving the woman congratulatory bear hug.