Alison Brie and Dave Franco are engaged.

The 'Mad Men' actress is set to tie the knot with the 30-year-old actor after over three-and-a-half years of dating, her representative has confirmed to E! News.

The 32-year-old beauty was pictured wearing her new engagement ring at a screening of her new movie 'Sleeping With Other People' in Los Angeles last night (24.08.15).

The notoriously-private couple never speak about their relationship and are rarely pictured together, even walking the red carpet separately at this year's Met Gala.

In 'Sleeping With Other People', Alison plays Lainey, who is obsessed with her cheating lover so seeks help at a support group for sex addicts, where she runs into her womanising first lover and they pledge to stay as friends and not ruin their bond with sex and the brunette beauty admitted she could ''relate'' to most of the themes of the film.

She told Refinery 29: ''To me, one of the major themes of the movie is self-worth, especially as it pertains to Lainey. She really puts so much of herself into her relationships. Then, her entire self-worth is in the hands of another person.

''It's something I could relate to from time spent dating... I definitely have had these kinds of talks with friends where they're sobbing about a guy, like, 'Why won't he call me back?' And it's like, 'You don't even like hanging out with him that much!'...

''I've also had a lot of good male friends. I guess my own personal life has defied the theme of this movie, which is that men and women cannot be friends. I say, 'Nay! They can!' ''