From the beaches to the b*tches, it looks like Justin Bieber is having a blast on his birthday trip in the Caribbean! But when there's a love triangle with one of the hottest young stars on the planet, someone's bound to feel left out -- and that ended up being Hailey Baldwin!

The other day the Biebs posted a few more snapshots from his 21st b-day trip, and while we thought he was somewhat serious about Hailey, he couldn't keep his hands off of former flame Yovanna Ventura! Of course, when it came time to play Apples to Apples, the pop star snuggled up next to Hailey, so clearly she's still his number one option...or is she?!

Nope! "Hailey left [early] because Justin was giving Yovanna all his attention," a source tells HollywoodLife. "She’s not his girlfriend and she tries to be cool but she’s not gonna be second best to some random girl."

The source added, "She didn’t throw a big fit, she didn’t pick a fight with Yovanna, she just left. She was supposed to stay until the end of the week but she bounced early. She’s not going to stay in a situation like that. She’s telling people she’s over it and doesn’t care but it’s messed up what he did.”

Justin posted a few photos of himself on a jet ski, and he also uploaded a shirtless shot snapped on his deck. "Great birthday â™› and I'm not fat it's the angle," he wrote. Um, after seeing his super sexy Men's Health cover yesterday, don't tease us with a shot where we can't see the whole package!