Jennifer Garner is ''okay'' with Ben Affleck's rumoured new romance.

The 45-year-old actor is believed to have struck up a relationship with 'Saturday Night Live' producer Lindsay Shookus after he and Jennifer, also 45, filed for divorce in April this year, following their 2015 split which came after an 11 year marriage.

And sources now say Jennifer - who has three children Violet, 11, Seraphina, eight, and Samuel, five, with Ben - knew about the romance before she decided to accompany the 'Live By Night' actor on holiday with their brood earlier this week.

An insider revealed to Us Weekly magazine: ''Jen knew about the new relationship and still chose to go on vacation with Ben for the 4th of July. She is okay with it.''

Ben and Lindsay are believed to have met in London recently, where Ben was working, and have enjoyed a number of dates, including going to see Sam Mendes' play 'Ferryman' in the English capital.

A source said: ''They are in the early stages [of their relationship]. It's more than a summer fling. They are having fun and care for each other. It's early and they are taking it slow.''

Meanwhile, it was recently revealed that Ben is ''working on himself'' after completing his stint in rehab.

The 'Batman vs. Superman: Dawn of Justice' actor revealed in March he had completed treatment for alcohol addiction, and sources insist the star is ''focusing on [his] family'' and working toward becoming a better person.

An insider previously explained: ''[He's] doing well. These two [Ben and Jennifer] consistently work on their relationship. While addiction can take a toll on a family, Jen was a true constant and - along with his friends - really helped encourage to seek extra support. Ben is focusing on family and working on himself.''

Ben and Jennifer - who tied the knot in 2005 - remain committed to co-parenting their children and are ''working hard'' to make sure their brood is happy.

The source added: ''They are working hard to continue to build a world that is right for their children. They spend quite a bit of time on this. They continue to co-parent and respect each other. I think some would be surprised to see how close their relationship remains.''