Casey Affleck Welcomes Jennifer Lopez 'to the Family' in Sweet Post After Skipping Weekend Wedding

The actor's girlfriend also revealed why Casey wasn't in attendance at the Georgia ceremony on Saturday.

A warm welcome. Casey Affleck shared some kind words for his new sister-in-law in a heartfelt message of support.

While Casey, 47, wasn't in attendance at Ben Affleck and Jennifer Lopez' lavish wedding ceremony held at Ben's estate in Riceboro, Georgia, on Saturday, the Gone Girl actor took to Instagram on Sunday to share a kind word for the songstress.

"Good things are worth waiting for," Casey wrote alongside a throwback photo from 2002, showing Casey walking with Ben and Jen during their first romance.

"Here is to twists and turns, new beginnings, and finding new reservoirs of old love," Casey wrote. "Welcome to the family. Get ready for some real dysfunction! Kidding. I am kidding."

He ended the post sharing, "Jen, you are a gem. We love you so much!!! ❤️"

Saturday's star-studded affair -- which came just a month after Ben and Jen first tied the knot in Las Vegas -- was officiated by life coach Jay Shetty and attended by the couple's family, friends and a slew of celeb guests, including Matt Damon, Kevin Smith and more.

However, Casey was not among those in attendance. Instead, he was in Los Angeles on the big day, and was spotted getting coffee at a Starbucks. When a paparazzi asked why he wasn't at the wedding, Casey said he had "other things."

Well, according to a comment on Casey's sweet post on Sunday, left by his girlfriend, Caylee Cowan, the father-of-two was in Los Angeles to take his 14-year-old son Atticus to soccer practice.

"Hey, if you weren’t in town Saturday to take Atty to soccer practice then who would’ve helped the kid who broke his arm?" Cowen shared, referring to an incident that must have occurred during said practice session. "You’re a good man. I love you."

Casey shares two sons, Atticus and 18-year-old Indiana, with his ex-wife, Summer Phoenix.

For more on Ben and Jen's wedding weekend, check out the video below.