Joe has been spotted with Chelsea Kane, Taylor Swift, Camilla Belle, Demi Lovato and Ashley Greene.
His date was more adventurous with her print dress, a sweet gold necklace with two charms and ombre colored hairstyle which Khloe Kardashian made popular last year.
While Nick's relationship with his beauty queen is rather new, Joe's romance with Blanda, 29, is well known.
They have been proudly displaying PDAs all over New York City for months.
The singer seemed totally immersed in Olivia at the tennis game, sitting close by her side.
Dressed casually in a beige and grey Polo shirt covered by a button-down royal blue shirt and wearing a leather and silver bracelet, the multi-platinum-selling artist looked like he wanted to blend in.
His beauty pageant girlfriend was more stylish in a black shirt, red mini skirt, and carrying a red Lacoste hat.A large gold bangle topped off the look and her fashionably oversized black purse was a smart accessory choice.The former model turned graphic designer hails from Switzerland and has been seen holding the singer's hand often, so these two are obviously not shy about being outed as a couple.In March there were rumours that the lovers made a sex tape.Joe, 24, quickly denied it and Blanda took to Twitter to respond: 'If anyone comes across this sex tape please make sure to send me a copy! :)'Both brothers have dated their share of celebrities.Nick has taken out Victoria Justice, Miley Cyrus, Selena Gomez and Delta Goodrem, to name a few.