I don't like the ending of the film. Karen remains in an unhappy marriage she thinks will be fixed by the baby she is carrying And I think Tina's views are valid as well.
But she made the mistake of not keeping the baby she was once pregnant with to please her husband, who at the time, also did not want to have kids, because at the time, she was willing to keep the baby, but let it go, because of an agreement she made with her husband, Wayne. It was also unfair of him to say she was not nurturing enough, because she did not want to get pregnant. She practically 'nurtured' him to the point where he began to change, and be aware of himself.
I feel she sacrificed her own desire for kids with him, only for him to leave her last minute because 'he changed his mind' and is allowed to do so. And now, because an opportunity presented itself; a baby on the way, accomodation, opportunity to stand on his own two feet, he's taken it, leaving Tina high and dry. I don't think he even appreciated that she stuck with him all this while.
Would her marriage have survived had she kept the baby a year ago? I don't know. But leaving her alone in the end, only re-enforces societal beliefs that a woman who does not want to have kids is selfish and deserves to be alone.
Women should be allowed to make choices about their bodies, careers, and lives, without being judged and boxed into societal expectations.