Dating

Dennis Quaid got his birthday celebration started early with a serious check of the ole ticker involving his girlfriend ... and a roller coaster.

Dennis and model Santa Auzina -- who's 30, btw -- hit up Six Flags Magic Mountain over the weekend and strapped themselves in for high-speed fun, and a lot of screaming.

He'll turn 63 on Sunday.

If the ride doesn't make him feel young, something tells us Santa will.

Alex Rodriguez brought a secret weapon to a business meeting Monday ... his GF, Jennifer Lopez.

Alex arrived at the NYC office building alone just before 1 PM ... we're told for a "post baseball opportunity." J Lo arrived shortly thereafter and they left together at 1:30.

We're told A-Rod respects J Lo's business acumen and wanted her there. He's been fielding offers since his retirement and we're told this meeting was important enough that he wanted her take.

Instagram hottie Jen Selter took her famous ASSets on a beach vacation, and it looks like she took a new bf too ... Big Time Rush singer James Maslow.

Selter and Maslow were down in Tulum, Mexico over the weekend. She's renowned on social media for her butt ... but James is pretty easy on the eyes too.

No word if they're actually dating, but check out the pics -- they seem, at the least, very friendly.

Maslow actually performed at the Maxim Spring party, so it might have started as a work trip -- but based on these pics he's mixing in plenty of pleasure too.

Nick Young's turning women off that baller life ... just ask his ex-GF.

We got Paloma Ford leaving Nightingale Plaza in L.A. (looking STUNNING, btw) -- and the singer gave some advice for women looking to date a professional athlete -- don't.

FYI, Nick and Paloma started dating back in September -- but the relationship fizzled in January.

Don't worry, things are working out just fine for Ford -- she recently signed with Master P and has some secret projects in the works.

J Lo and A-Rod seem to be sending silent messages to the world they're perfect matches for each other.

J Rod (sorry, had to do it) were arm-in-arm Friday ... both decked out in beige outfits while they hit up what looks like their fave NYC restaurant. For the second day in a row they dined at Marea in Midtown. Even rain showers couldn't stop 'em.

Little rain, little shine -- but damn they are fine. Just sayin' ...

Paris Hilton might be smitten with her new boyfriend, actor/model Chris Zylka, but her parents don't seem to think she'll be walking down the aisle anytime soon.

We got Kathy and Rick Hilton leaving dinner at Catch Thursday in West Hollywood. Rick seemed to be Team Zylka, but pumped the brakes when we mentioned wedding bells.

Paris told us she's found the one in Chris, but she's been there before. Her folks know the game.

Basic guys dreaming of dating Malia Obama can take a seat ... the former First Daughter looks to have a suitor who is anything but basic.

Malia and the mystery guy were cruising through SoHo Wednesday night -- looks like they had a 3rd wheel girlfriend with 'em though. As for the dude, he was pretty stylish in a long black coat and knitted cap.

More than anything ... we know he's TALL. Both Malia and Barack are 6'1", and this guy looks to have a good 3 inches on her.

Magic Johnson has a rule when it comes to dating his daughter ... NO DODGERS ALLOWED!

Of course, Magic is a co-owner of the MLB team -- and his daughter, Elisa, says he's not a fan of her mixing business with pleasure.

In fact, when it comes to dating -- "He's a no-go on the athletes and Dodger players."

The Weeknd was all about Selena Gomez's public cuddling ... until he noticed paparazzi watching.

Paps got the couple Tuesday showing some extreme PDA while strolling around Buenos Aires before Abel's gig later this week.

He seems down with her clinging onto him ... but watch what happens when he sees the camera guy across the street.

J Lo and A-Rod are already looking like an old married couple -- an old, stupidly RICH married couple -- that still loves hanging out with each other and their friends.

The couple did a double date Monday night at the Sunset Tower Hotel in L.A. We're told the group of 4 dined for a little over 2 hours, and judging by the expressions on both their faces ... had great conversation with their meals.

Selena Gomez had the best time watching The Weeknd from backstage ... her face confirms it.

Abel was performing Sunday in Brazil for his Starboy tour -- and Selena's clearly enchanted watching from afar.

Malia Obama may have dodged a bullet by not taking Swae Lee up on his date offer because he’s already got other chicks he’s eyeing.

We got the Rae Sremmurd rapper at LAX where he told us he’s given up on that dream date with the former president's daughter ... where he'd whisk her off her feet and dine in the clouds.

Rejection is never easy, but Swae seems to have a solid backup plan.

'Bachelorette' Rachel Lindsay went on a horse date in Beverly Hills of all places.

Rachel was shooting a segment of her show Thursday at Beverly Gardens Park with one of her 25 suitors. It's pretty hilarious ... check out the tudor-style mansions in the background.

It is, after all, the wild wild West in them thar hills ... and just a stone's throw from the Polo Lounge.

"Stranger Things" stars Natalia Dyer and Charlie Heaton play Nancy Wheeler and Jonathan Byers on the show, and their relationship seems as complicated onscreen as it's off.

There are rumors the two are dating, and when we caught them together at LAX Wednesday they hinted that mixing work and a relationship is no big deal since everyone's just one big family on set.

Charlie stopped short of a confirmation though, but it's pretty obvious.

Paris Hilton is shackin' up with her new BF and is ready for a walk down the aisle.

We got Paris and 'Leftovers' star Chris Zylka strolling through LAX Wednesday in a handlock, when she dropped the news ... she's off the market for good.

It seems Alex Rodriguez's sister has already decided Jennifer Lopez is the one for him ... cuz she posted a pic with the singer and claimed her as a member of the family.

A-Rod's sis, Susy Dunand, posted a couple pics with J Lo Friday ... but it was her caption that raised eyebrows, using "#miscuñis" -- the Spanish word for "sister-in-law" -- in the post.