The JLS star dated the 22-year-old for eight months before their separation last November.
The couple confirmed their reunion in January after being spotted together by the paparazzi.
Humes is now said to have picked out an engagement ring for Wiseman, but will wait to pop the question on a romantic trip to the Maldives in the new year.
"Marvin's booked an appointment at Tiffany & Co," a source told Heat. "That's where he bought her the commitment ring when they got back together."
Humes previously admitted that he was thinking of moving in with Wiseman and couldn't wait for them to have children.
Humes and his JLS bandmates premiered their latest single 'She Makes Me Wanna' earlier this month.
Watch the video for 'She Make Me Wanna' by JLS below.