Alex Rodriguez wants to give Jennifer Lopez ''all the happiness'' she deserves.

The 42-year-old baseball superstar took to Instagram on Tuesday (24.07.18) to celebrate his girlfriend's 49th birthday with an adorable tribute, accompanied by several photos the 'Shades of Blue' actress.

He wrote: ''When we were kids, birthdays were exciting because it was all about the gifts we would be getting. A new bat, dance shoes, maybe a new CD (yes I'm old!). I see firsthand how that's changed for Jennifer, and how she's found joy in sharing with others. For someone who has been about giving everything she has 365 days a year--to our children, our families, the world--I hope today, we can give you all the happiness you deserve. I love you mucho Macha 13. (sic)''

Alex and the 'On The Floor' hitmaker are currently on vacation in the Bahamas with their children - Jennifer's 10-year-old twins Emme and Max, whom she has with Marc Anthony, and Alex's daughters Ella, 10, and Natasha, 13 - for joint birthday celebrations, as Alex is set to turn 43 on Friday (27.07.18).

And according to sources, the family couldn't be having more fun on their special getaway.

They said: ''[They spent] their first day at the beach playing in the water and building castles in the sand. The kids are all very good friends and love hanging out together. They were running around playing games and splashing in the water.

''J-lo and A-Rod watched them [the kids] from the shore and were taking pictures of everything. They loved being outside and strolling along the beach.''

When the sun began to set, the family gathered together to watch the sunset before heading back inside for dinner.

The insider added to E! News: ''In the evening, they watched the sunset while the kids played in the water. It was beautiful and peaceful with nobody around. They just listened to the waves as a family and then went right inside their house for dinner.''