Jennifer Lopez has poured out her heart in a gushing Instagram post to celebrate her boyfriend Alex Rodriguez's birthday.

The superstar took to social media on Friday (27Jul18) to share a video montage featuring personal footage of the couple laughing together, goofing around, and singing in the car, as well as snaps of the retired baseball ace spending time with his daughters Natasha, 13, and Ella, 10, and images of Alex bonding with Jennifer's twins, Max and Emme, also 10, from her marriage to Marc Anthony.

"Baby, spending time with you over the past year and a half ... getting to know the real you more and more ... I am surprised everyday (sic) by the generous, loving person you are to me and everyone around you...," she wrote in the lengthy caption.

"you bring energy and laughter everywhere you go. But I am most impressed by the man you strive to be ... growing everyday ... reaching for new heights, new understanding, new dreams and new goals."

"YOU ARE A SUPERSTAR, a force of nature, a visionary and a gentlemen," J.Lo continued. "I love you and I wish for you, today and everyday, all the goodness and abundance God and the universe has to offer ... HAPPY BIRTHDAY Macho Bello. Te Adoro (I adore you)."

Jennifer also threw a party for her man on Saturday and led friends and family in a rendition of Journey song Faithfully, with the birthday boy posting a short clip of the performance on Instagram, which ended with the singer/actress declaring, "Happy birthday, baby, we love you!"

"Now this is a party!," he wrote beside the post. "Thanks @jlo for leading the serenade... I'm an '80s rock guy at heart ..."

The bash capped off a week of celebrations for the couple as Jennifer rang in her 49th birthday on 24 July (18) with a little family beach time.