The 21-year-old star admits that it hasn't been easy for Calder to adjust to the amount of attention he receives as a member of the chart-topping boy band, reports femalefirst.co.uk.
"It hasn't been easy at times. She gets pretty intimidated by it all. I mean, who wouldn't? She can't have Twitter or anything like that. At first, I was like, 'Just chill out a bit, it's fine', but now I understand where she's coming from," Tomlinson told The Sun newspaper.
"I can't expect her to deal with some of the stuff so easily. But with that said, I couldn't be happier with her," he added.