JAKE GYLLENHAAL is living it up as one of Hollywood’s hottest bachelors, but his sister Maggie thinks he’d be better off settling down and having a family, like her.

Hunky Jake, 32, star of hit films such as “Source Code” and “Broke­back Mountain,” hasn’t had a serious girlfriend since his split from Reese Witherspoon in 2009. And he’s currently dating sexy swimsuit model Alyssa Miller, who’s nearly 10 years younger.

MEANWHILE, BIG SIS Maggie Gyllenhaal, 35, is happily married to actor Peter Sarsgaard and they have two adorable girls together, Ramona, 6, and 1-year-old Gloria.

“Maggie doesn’t think Jake is being serious about his life,” said a source. “She thinks he’s acting frivolous and he needs to work harder to find true happiness like she has.”

But according to a friend, Jake be­came a commitment-phobe after his heartbreaking bust-up with Reese.

“It was really a kick in the stom­ach to Jake,” the friend said. “He thought they were going to get mar­ried and spend their lives together.”

And it was only salt in Jake’s wounds when, within weeks, Reese started dating Hollywood agent Jim Toth. The two wed in 2011 and now have a 9-month-old son, Tennessee.

York City coffee shop, but Maggie – now starring in “White House Down” – is lobby­ing him to rekindle his romance with his first true love, “ Spider -Man ” beauty Kirsten Dunst.

“Maggie’s always pushing Jake to give Kirsten a call,” said the source. “And while Jake loves his sister, he in­sists that he’s perfectly happy being out there on the dating circuit.”