This Unknown Woman, who can be referred to as Jane, was seen the morning half undressed in Dash Gardiner's house. Ingrid was immediately jealous when she found out that Dash slept with Jane. Dash most likely broke it off with her and she hasn't been seen since.
In The Old Man and The Key, she is seen sleeping in Dash's bed and asking him if everything is okay.
In Sex, Lies, and Birthday Cake, she sweetly says 'hi' to Ingrid as she's dressing and ready to have breakfast with Dash. She is not seen again after this. It can be assumed that Dash ended it with her after hurting Ingrid.