Big Brother is a game with a lot of money at stake, and an odd set of circumstances where people spend pretty much every minute with each other for months.
It’s possible the mostly-platonic-seeming nature of their relationship will grow into something more when they’re out of the house.
Natalie explained her reasons for saying what she did, and either she didn’t think she was so obviously betraying James with what she said, or she genuinely didn’t mean to.
As for whether or not James and Natalie will date after the show, Natalie answered with optimism about some kind of relationship, but she didn’t seem certain that it would involve a romance.