Is Pippa Middleton too busy to give time to boyfriend Nico Jackson?

The sister of the Duchess of Cambridge was snapped taking a walk near her office in Chelsea after a grueling biking marathon from London to Brighton.

"Dressed in a low-key striped top, a leather jacket and a pair of faded skinny jeans, the writer and nutritionist peered intently at her mobile phone as she walked," Daily Mail said.

On Sunday, Pippa Middleton completed the charity marathon for the British Heart Foundation, where she serves as an ambassador for two years now.

"A keen cycling fan, Miss Middleton rode across the US last year on behalf of the charity and is regularly seen biking around London," it added. "Speaking to local paper the Brighton Argus at the end of the race, she told of her enthusiasm for the sport and said it is something that 'everyone can enjoy.'"

Earlier this month, Life & Style magazine reported that Pippa Middleton and Nico Jackson are already engaged.

"Kate is so happy for Pippa and she loves Nico. They all get along so well!" the source said.

In fact, the Duchess of Cambridge even help picked the engagement ring.

"It will definitely be a stunner," the source said of the engagement ring to be given to 31-year-old Pippa Middleton.

Pippa Middleton and Nico Jackson have been dating for three years now, and the engagement rumors came on the heels of the report that they have broken up after he move on a new job overseas.

Also last month, the socialite party planner was caught on a night out with her ex-boyfriend James Matthews in Soho in London. Pippa Middleton being caught with ex-boyfriend James Matthews came on the heels of the rumors that she has broken up with Nico Jackson who left London for Geneva.