Ever since it was revealed that Ben Affleck was dating "Saturday Night Live" producer Lindsay Shookus, many have been wondering about how estranged wife Jennifer Garner feels about their brewing romance.

According to reports, the 45-year-old American actress is not too happy about it.

"It's not an easy situation for Jen," a source close to Garner told PEOPLE, adding, "She knew it would happen soon. Ben just can't be alone... It would have been easier for Jen if Ben would have just dated someone that Jen wasn't familiar with."

It is rumored that the "Batman v Superman: Dawn of Justice" actor had a secret affair with Shookus a year and before he and Garner split. At the time, Shookus was also married to her former "Saturday Night Live" colleague, Kevin Miller.

Further fueling the rumor mill, another source revealed to Us Weekly that Affleck and Shookus were not casually dating; they were having an all-out illicit relationship. They were allegedly already sleeping together, exchanging romantic messages and meeting up whenever they could.

Affleck and Shookus' budding romance comes three months after he and Garner — who share three kids together, Violet Anne, Seraphina Rose Elizabeth and Samuel — jointly filed for divorce.

Currently, Affleck is busy filming for "Justice League." In the upcoming superhero film, he reprises the role of Bruce Wayne aka Batman, the benefactor of the group of meta-humans consisting of Arthur Curry/Aquaman (Jason Momoa), Victor Stone/Cyborg (Ray Fisher) and Barry Allen/Flash (Ezra Miller).

The "13 Going on 30" actress, on the other hand, will be seen next in "The Tribes of Palos Verdes," an upcoming coming-of-age movie based on Joy Nicholson's young adult novel. The film follows the life of a family who moves to a well-off suburb of Los Angeles called Palos Verdes.