David Hasselhoff doesn't know why his girlfriend keeps turning down his proposals.

The former 'Knight Rider' star has been in a relationship with Welsh beauty Hayley Roberts since 2011 and he has popped the question five times but has received a ''no'' on each occasion.

Hasselhoff insists they're still a very happy couple but he's going to hold off on his wedding plans for now.

When asked why Hayley keeps saying no to his offers of marriage, the 62-year-old actor said: ''I don't know. That's the question everyone asks me. That and babies. Right now I've got so much happening, we're taking things a day at a time. We're happy where we're at and we'll see what happens.''

Hasselhoff - who can be seen in new UK TV show 'Hoff The Record' this week - is enjoying one of the busiest periods of his entire career and he's determined to make the most of it.

The ex-'Baywatch' star told the Metro newspaper: ''I can't sleep at night because so much weird stuff is happening at the same time. You're only as good as when your phone rings and for many years it wasn't ringing ... I can't explain it, all I can say is it's down to hard work ... I'm playing with the big boys again again for a change and we'll see what happens. If it lasts, it lasts, if it doesn't I'll continue to work - I've got a great relationship with my fans.''