Behati Prinsloo is still in shock over her engagement.

Maroon 5 frontman Adam Levine proposed to the brunette beauty over the weekend and Behati, 24, admitted she is still adjusting to being a fiancee.

She told 'ET Canada': ''I am so happy and excited and still can't believe it's true! It was a one-knee thing! It was serious, it was very old school!''

Adam and Behati - who first began dating in May 2012 and split earlier this year - surprised everyone with their engagement as Adam, 34, was spotted on holiday with Sports Illustrated swimsuit model Nina Agdal last month.

However, the romance was short-lived because Adam was still besotted with Namibian born model Behati.

An insider said: ''The Nina thing was not that serious and was not going to last. After Adam broke up with Behati, he couldn't stop thinking about her. He knew he really loved her and wanted to be with her.''

Announcing the engagement, Adam's representative said: ''Adam Levine and his girlfriend Behati Prinsloo are excited to announce they are engaged to be married.

''The couple recently reunited and Adam proposed this weekend in Los Angeles.''