The singer only got engaged to the model in July but he has told the 24-year-old beauty he wants the wedding to take place immediately, reported Star magazine.
"Adam is in a mad rush to marry Behati ... The sooner the better," a source said.
The 'Payphone' hitmaker has let Behati know that money is no obstacle when it comes to planning their nuptials and he is happy to spend a million dollars on their big day.
"He's ready to become a husband and father so he told Behati to spend whatever she wants, even a million dollars, as long as the wedding is in the near future," the source added.