But what about Ben's new girlfriend, "Saturday Night Live" producer Lindsay Shookus?
After Lindsay, 37, and Ben, 44, went public with their relationship on July 6, the world quickly learned that she had split from her husband, "Late Night With Seth Meyers" producer Kevin Miller, a few years ago. (They married in 2010.)
But now a new report from Page Six claims that Ben isn't the first Hollywood star Lindsay has romanced.
"In addition to Affleck, Shookus has previously been linked to Jon Hamm, who has hosted three times and made six guest appearances on 'SNL,' according to multiple sources," Page Six reported on July 15 in a lengthy story about Ben and Lindsay's relationship.
The New York Post's gossip column also cited a source who spotted Lindsay and the "Mad Men" star, 46 — who split from longtime love Jennifer Westfeldt in 2015 after 18 years together — "looking cozy at a Kanye West concert at Madison Square Garden last September."
Jon's rep, however, denied a romance, telling the Post that though Jon knows Lindsay from "SNL," they "haven't dated. They are not friends, they are acquaintances."
Jon isn't the only famous guy to whom Lindsay's been linked.
An "SNL" colleague tells Page Six that there are rumors Lindsay, who books the sketch comedy show's top talent, has also dated Chris Noth, 62, of "Sex and the City" fame.
Chris's rep did not respond to the Post's requests for comment.
Though some reports have claimed Ben and Lindsay didn't start dating until both were separated, multiple outlets including Page Six, People and Us Weekly cite sources who insist the pair started their romantic relationship long before either had ended their respective marriages.
Page Six and other publications also claim Jennifer, 45, confronted Lindsay about the alleged affair four years ago after discovering texts between her and Ben, but that the producer "refused to stop" the relationship, a Hollywood source told the Post.
Jennifer also reportedly filled in Lindsay's husband on what was going on between their spouses. She's believed to have dropped the bombshell backstage when she appeared on Seth's show, where Kevin works. "Kevin had an inkling [about the affair], but there was a lot he did not know," the Hollywood source told Page Six.
On July 8, Us Weekly reported that Lindsay actually left her husband to be with Ben.
So how did it all start?
The Hollywood source told Page Six that Ben and Lindsay met on the "SNL" set (he's hosted five times) and that they began their relationship in 2013, just months after Lindsay gave birth to a daughter with her husband. Ben and Jen's son Samuel would have been around 1 at the time.
Ben then "adorned [Lindsay] with gifts… all these bracelets and rings," a publicist close to the situation told the Post, adding that "He was here in NYC all the time visiting her and no one knew."