Things seem to be getting really serious!

Ben Affleck joined girlfriend Lindsay Shookus, her parents, and her daughter Madeline on a hike over the weekend, and it's the first time we've seen him playing stepdad to the SNL producer's little girl since they began dating. This pic has gotta sting for Jen Garner!

Just one night earlier, the Oscar winner grabbed dinner with the Shookus clan at Cassia in Santa Monica, and apparently he gets along swimmingly with his potential new in-laws.

"Ben was in a great mood. Lindsay seemed very happy to have her parents here. You could tell Ben gets along great with her parents. They were all chatting and laughing. They shared a family style dinner with several of the restaurant favorites, including chickpea curry and steak frites. Ben picked up the check at the end of the night," an eyewitness at the eatery told People.

A source tells X17:
    "Lindsay is thrilled that all these relationship milestones are happening. They recently moved in together, now he's met the parents, and he's spending time with her daughter. She is telling friends she's expecting a proposal sooner rather than later, because he wouldn't be doing all of this and going out of his way unless he planned on spending the rest of his life with her."

We've learned from Leann Rimes and Eddie Cibrian that sometimes affairs do work out!