“Prime,” as its title aptly suggests, is about two lovers each at the height of their sexuality: an older woman and a much younger man.

Throw in the younger man’s devoutly Jewish mother as the older woman’s therapist, and you have one complicated plot line.

The story begins with the 37-year-old Rafi (Uma Thurman) and 23-year-old David (Bryan Greenberg), who are immediately attracted to one another but are at a loss about how to address their 14-year age gap. As their relationship becomes more passionate than practical, therapist/mother Dr. Lisa Metzger (Meryl Streep) is torn between concern for her patient and her son.

At first, watching the characteristically tough Thurman portray the vulnerable Rafi is a little hard to swallow. Thurman has trouble toning down her trademark personality without losing it altogether and seems to be merely reciting the dialogue in the first few scenes. However, as her character develops throughout the movie, Thurman does seem to better adapt to her role.

Greenberg fits his character well, but director Ben Younger seems to be trying too hard to prove David is cute and funny through his constant shirtless scenes and trivial exchanges with Rafi’s doorman.

We get the typically laudable performance from Streep, who is undoubtedly the most entertaining to watch. As she bites her tongue in her hilarious therapy session scenes with Rafi (which comprise the only appreciable dialogue in the film) and butts her disapproving nose into every area of her son’s life, Streep’s plausible contradiction of her goodwill and motherly paranoia carries the film through its humorous irony and ethical controversies.

Streep cannot, however, compensate for the film’s lack of focus. What starts out as an implausible and hilarious situation is drawn out into a more serious drama than we care to see. Not only does the needless introspection of Rafi and David’s relationship become exhausting, the overall direction is choppy and overdone. Younger seems to be trying to achieve a sort of omniscient view of the couple through abstract camera angles and grainy flashbacks, but the effect is more startling than intuitive.

What is commendable about this movie is its attempt to address the reality of such an unconventional relationship. But because it tries so hard to be impressive and taboo at the same time, it fails. This story would have been much better if it was a romantic comedy.