The JLS singer explained to Now magazine that a month may pass by without seeing loved ones.
"You can see them really every single day for a month and then we might not see them for a month," he said. "There's never really a set time, that's why you have to cherish your time you have got with them."
The Saturdays singer and Humes split in 2010 due to their busy schedules, but reunited in January.
Humes also revealed that he has given Wiseman a promise ring as a symbol of his commitment to her while the group are away.
Fellow JLS member Oritsé Williams hinted that the pair may be getting engaged in the near future.
"[The ring's] one step down from an engagement and kind of like a test before the real deal goes ahead," he added. "Marvin and Rochelle are really happy together. They're great right now."
> JLS Marvin Humes 'to propose to Rochelle Wiseman'