Justin Timberlake’s grandmother is worried his marriage is “hard going”.

The US singer-and-actor wed Jessica Biel in October 2012 but there has been constant speculation about their relationship. So much was read into Jessica not attending last year’s American Music Awards with her spouse, she took to Twitter to insist she was happy watching from home.

Now Justin’s grandmother Sadie Bomar has waded into things, hinting she has some concerns.

“They are married but they are so busy, both of them; it’s hard going. I’m sure when it’s right to have children they will, but not now,” she told British newspaper The Sun.

“They do love each other dearly but they are apart so much it’s going to be hard going for them.”

Sadie fears things are especially difficult for Jessica. Justin has been away a lot of late as he’s been promoting his music and films such as last year’s Runner Runner. His elderly relative believes the pair will make it work though as they are so good together.

“If he’s not coming back at night that puts a strain on things, of course it does,” she said.

“It’s hard to keep it all going but you have to have faith to keep it all going.

“I have faith in them and I believe they love each other dearly but I know they need time together.”

At the end of last year Jessica hinted she was starting to think about having a family. She admitted she “definitely” wants to be a mom, but remained evasive about exactly when that would happen.

“I don't know. I'm not quite sure about sooner or later, but definitely at some point,” she said.