The marriage was to have taken place on Saturday (July 28), but there were too many arguments between Usher and Foster, who is pregnant.
The ceremony was called off just hours before schedule, and Usher’s mother was also part of the problem, as she disapproves of the marriage.
One source told People magazine, "Usher’s mother (and former manager, Jonetta Patton, whom he fired in May) is against the wedding. That is one of the main obstacles. They only decided two weeks ago to have a wedding. They wanted to have it take place before the baby bump started showing."
Another source added, "Usher changed his mind. They had a lot of differences about the details. For example, the bride wanted barbeque, (Usher) wanted to have (renowned chef) Jean Georges cook."
Usher’s spokesperson, Patti Webster, refused to divulge if the star and his fiancee are still a couple.