The `Revolutionary Road` actress - who separated from her film director husband Sam Mendes in March - has reportedly called time on her romance with male model Louis Dowler after just four months of dating.
Despite being "very grateful" to the 35-year-old hunk for allowing her to get over the breakdown of her marriage, Kate is said to have ended the relationship to "concentrate on her career and children".
A friend of the star told MailOnline: "Louis was just the tonic Kate needed after her painful splitfrom Sam and they had a wonderful time. However, they have realised their relationship isn`t working and Kate needs space to be on her own.
"She is very grateful to Louis for helping her pick her life back up after her marriage ended and they had a lot of fun together, but she felt it had come to an end and wants to concentrate on her career and children."
Prior to the split, Kate - who has a six-year-old son Joe with Sam, as well as ten-year-old Mia from her first marriage to director Jim Threapleton - had reportedly been contemplating marriage with the British model.
A pal recently said: "As far as Kate is concerned, they could go all the way together - get married, have kids. She`s the happiest we`ve ever seen her, he really brings out a wonderful, carefree side to her that we haven`t seen for years."