Mila Kunis "looked like part of the family" at Ashton Kutcher's brother's wedding.
The 'Forgetting Sarah Marshall' star and her boyfriend went to St. Simons Island in Georgia, US, to attend the wedding of Ashton's twin brother, Michael, to Kate Hightower on Saturday.
An onlooker told E! news Ashton looked "chill and comfortable" during the ceremony, adding Mila also looked very comfortable and relaxed among Ashton's relatives.
A reception was held at the same location as the ceremony, a private residence, with guests spending the night in a cottage house.
The source added: "Overall it appeared everyone had a great time."
Mila Kunis at the Golden Globes
Mila, 30, and Ashton, 35, are getting to be old hands at being wedding guests, as last year they attended her brother's wedding to ballet dancer Alexandra Blacker in Florida.
Despite engagement rumours Mila has previously claimed she isn't interested in getting married herself.
She said: "I would love to find 'The One'. But I'm not sure about marriage. I see no need. I'll be with somebody because I want to, not because a piece of paper tells me I have to. That said, if the love of my life thinks it's important, then fine, I'll get married."