"You won't be happy with her."
Translation:Nebudeš s ní šťastný.
"You won't be happy with her" can mean two things: 1) Your life with her won't make you happy, 2) She's done a bad job and you will be angry with her. Thus, in Czech, 1) "Nebudeš s ní štastný," 2) "Nebudeš z ní šťastný" are both correct answers and shall be accepted. Thank you!