“Our Son” is a child care/child custody soap opera about married gay couple who divorce and then fight over who gets primary custody of their son.

It’s a sensitively-mounted drama that bears more than a passing resemblence to “Kramer vs. Kramer.” And if “soap opera” seems a harsh way to describe “Our Son,” remember what Dustin Hoffman said when he finally got that first Oscar — “Well, the soap opera won!”

Billy Porter plays Gabriel, doting and spoiling “Poppa” to eight year-old Owen (Christopher Woodley), the one who takes him to school, picks him up, takes him to the park and reads him a bedtime story every night.

Luke Evans is husband Nicky, a small-imprint publisher who supports them in style and comfort. But as “Daddy,” he treats parenting as an afterthought. He kind of resents the kid being allowed into their bed at night, and is a little tougher about the indulged child’s upbringing.

We can see the imbalance, right from the start in this Bill Oliver (“Jonathan”) film. It’s not a subtle. But even if we can sense what’s coming, it’s a bit of a jolt.

“I’ve met somebody.”

It’s the stay-at-home father who says this, the long-unemployed actor who has devoted eight years to this boy — born via surrogacy — and kept a home in this 13 year relationship.

Although they’d talked of making theirs an “open” marriage, this is a shock to the system and abruptly ends things. Not in Nicky’s mind. He keeps hoping this can be fixed. Gabriel?

“When you live with somebody for a long time, sometimes they get on your nerves,” he explains to Owen.

“Our Son” is about these two and their escalating fight for primary custody. It’s plain that the boy prefers his Poppa. It’s just as obvious that the jilted Nicky — the film is mostly from his point of view — isn’t giving up the child without lawyers and a fight.

The best moment here might be when Nicky’s talking to his gay attorney (Robin Weigert), saying “Isn’t there anything I can do?” She wakes him up with a cold, dry slap of reality.

“No. He filed for divorce.” That’s it. Even if Gabriel’s fling turned out to be commitment-phobic, even if he’s wholly reliant on Nicky’s support, he is out of here and he wants their kid to live with him. After he gets a place. After he finds a job to pay for that place.

The film pushes each character’s grievances into the foreground, briefly, and finds each allies who support his victimhood in all this.

The story has a gentleness that plays well, and the leads click. I like the way Oliver & Co. create this gay world of (New York) dinner parties, gay lawyers and gay friends who try not to take sides.

Each character has parents (Phylicia Rashad and Kate Burton) who shake their heads and ask versions of “I hope you two know what you’re doing.”

But “soap opera” is a label that implied shallowness, and that’s another hallmark of this narrative. Gabriel’s lack of acting success and supposed lack of marketable skills can be magically solved with a connection. They’re not just a gay couple with “roles” mimicking the stoic, emotionally-stunted “father” figure and femine, nurturing “mother” with a touch of the dramatic and emotional about him.

“I, I, I ATTENDED to him,” Porter’s Gabriel huffs in tones that would make Joan Crawford proud.

They have pregnant lesbian friends and a demographically-correct pool of acquaintances in their world, which contributes to the feeling that is merely a gay variation on a tried and true divorce/custody formula.

“Sweet” and “sensitive” may win the day. But this fight over “Our Son” is a little bland and predigested, and even if that underscores the point that marriage and family and the dynamics that create dysfunction are all the same (“Open marriage” included.), that doesn’t give this affecting film much room for surprise.

Rating: R for some sexual content/nudity and (profanity).

Cast: Luke Evans, Billy Porter, Christopher Woodley, Phylicia Rashad and Kate Burton

Credits: Directed by Bill Oliver, scripted by Peter Nickowitz and Bill Oliver. A Vertical release.

Running time: 1:44