@Mario32 said:

What's the name of the actress who plays the woman in the red dress at the party?I can't remember the character's name.

The woman (Laura James) in the middle of this image?

https://www.imdb.com/title/tt13701962/mediaviewer/rm184871937/

Or this woman in the background?

https://www.imdb.com/title/tt13701962/mediaviewer/rm235203585/

Or the woman (Laura James, who is the same woman in the image above) in the trailer?

https://www.imdb.com/video/vi1757528857?ref_=tt_pv_vi_aiv_1

I don't think it's either of those.When they went to the party at the house a group of women who obviously dated the main character before he got married showed up and one of them was a brunette who was wearing a red dress.THAT'S who's name I'm looking for.

@Mario32 said:

I don't think it's either of those.When they went to the party at the house a group of women who obviously dated the main character before he got married showed up and one of them was a brunette who was wearing a red dress.THAT'S who's name I'm looking for.

I haven't seen the movie (only the trailer) but from the trailer, the woman in red (Laura James) is obviously an ex-girlfriend.