Her love don’t cost a thing … with the exception of a hired P.I.!

Jennifer Lopez hired a private investigator to follow her boyfriend, Alex “A-Rod” Rodriguez, according to Us Weekly.

An insider tells the magazine that the actress-singer, 47 — who, incidentally, plays NYPD detective Harlee Santos on NBC’s Shades of Blue — employed a P.I. to keep an eye on the retired MLB legend, 41.

MORE: Jennifer Lopez’s Twins Are Super Excited About Her Engagement to A-Rod! (EXCLUSIVE)

“He found out and they had a huge fight,” the source said. “But they’re working through it.”

This report comes after The National Enquirer published an interview with A-Rod’s alleged mistress Lauren Hunter earlier this year. Rather than call it quits then and there, the “Waiting for Tonight” songstress reportedly sought help from a professional detective to preserve her relationship with the athlete.

View this post on Instagram

Ni tu Ni yo ❤️ #preshowpic

A post shared by Jennifer Lopez (@jlo) on

It’s no surprise Jen is doing everything to make things work. An insider previously told Life & Style that Jennifer — who recently accepted a proposal from Alex during a romantic trip to Paris — can’t wait to settle down with the former baseball star. Plus, she is looking forward to merging their families.

Since they started dating earlier this year, Jennifer’s nine-year-old twins, Max and Emme (whom she shares with ex-husband Marc Anthony), have become besties with Alex’s two girls, Natasha, 12, and Ella, 9, from his marriage to ex-wife Cynthia Scurtis.

MORE: J.Lo Drags Haters Who Accused Her of Photoshopping Her Ab Selfie Because No One Messes With Jenny From the Block

“J.Lo can’t wait for them all to be one big, happy family,” the insider said. “This is a real dream come true for her.”

Despite Jennifer’s reported doubts, Alex seems just as enamored. During a March 31 appearance on The View, he couldn’t help but gush about his superstar girlfriend.

“We’re having a great time. She’s an amazing, amazing girl. One of the smartest human beings I’ve ever met and also an incredible mother,” he said at the time. “She just likes simple things. I mean, she’s a very, very simple person. Loves family. Is a great sister. Is a great daughter.”