A post shared by Lea Salonga (@msleasalonga) on Jun 5, 2017 at 5:16am PDT

A touching love letter from Aga Muhlach to Lea Salonga, in which he called his onscreen partner as "the one that got away," has driven their fans into a frenzy.

Over the weekend, a Twitter user discovered the affectionate note, which was first made public four years ago in Salonga's book "Playlist -- A Celebration of 35 Years." The post immediately went viral, garnering tens of thousands of likes and retweets.

The heartfelt letter began with Muhlach revealing that his "Sana Maulit Muli" co-star never knew that he loved her.

He went on to recount how being paired with Salonga for 1992's "Bakit Labis Kitang Mahal" resurrected his career, and the profound effect working with the legendary singer had in his life.

"Lea is the one that got away. And she never knew," an excerpt read. "So now she knows. We are older and wiser now, we have gone our own ways, we are no longer the same. But the fire has not ebbed."

"Rather it has grown deeper, stronger, quieter, more enduring. I love her still, but perhaps because she got away, I have her as a friend now, and so I will always have her," Muhlach added.

Here's the copy of the whole love letter. ❤️ pic.twitter.com/kONdjQD9Mz

— Ariella Sandra (@ariellasandraaa) June 25, 2017

The letter reignited calls for a third movie starring Salonga and Muhlach, which Star Cinema announced in 2015 but had to be shelved due to scheduling conflicts.

Salonga, who is currently part of the ongoing "The Voice Teens," has said that fans may be in for a "very long, long, long wait" for the planned project.

Early this month, the two were spotted out for dinner with their respective spouses (picture above). Salonga is married to Robert Charles Chien, while Muhlach is married to Charlene Gonzales.