Solange Knowles has had the “perfect” birthday.

The younger sister of superstar Beyoncé celebrated her 28th birthday yesterday and shared a snap of what she got up to on her special day.

On Instagram she treated fans to a picture of herself with boyfriend Alan Ferguson, taking a dip in the sea. The photo shows the singer grinning at the camera, with her arms wrapped tightly around her beau.

“Today couldn't have been more perfect. I couldn't have smiled harder. Thank you for all of your lovely and wonderful wishes. They warmed my heart and I simply feel grateful for all of the love. (sic)” she wrote on the site.

It could be that yesterday was a double celebration for the pair. Website Media TakeOut claims the couple are now engaged.

“An MTO snitch just dropped the word. Solange Knowles and her longtime boyfriend Alan Ferguson got engaged last night. The two have been dating now for almost five years,” the outlet claims.

Solange was previously married to Daniel Smith and they have a son, nine-year-old Daniel Julez, together. In 2007 she confirmed they had divorced, but their relationship is friendly.

"We co-parent really well," she previously told Harper’s Bazaar. "I'm able to say, 'I need to finish this album, can you step up and take care of the boy?’”

She’s now happy with Alan, but admitted it doesn’t make for interesting music.

"Luckily, I dated all of the losers ages ago. My love life has been stable for a while," she smiled.

"It's a f**ked-up thing - without conflict it's a lot harder to write interesting songs."

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