Teen Mom OG Promises: How Zach Proposed To Cheyenne -- And Ryder

For starters, the mother-daughter duo got matching rings

Cheyenne and Zach made a "commitment for a lifetime" during tonight's Teen Mom OG episode: The longtime sweethearts got engaged in front of their family and friend's at their baby sprinkle for son-on-the-way Ace. Ryder was also part of the special moment.

Before Zach popped the question to Chey and Ryder, he made sure to get the blessing from her father Kyle. Next, he devised the plan: The proposal(s) would unfold at the aforementioned party in a separate indoor area, and the two would be blindfolded on their way to the special spot.

When Cheyenne arrived at the romantic destination, she was genuinely surprised. And no, Chey, you weren't receiving a crib!

"Twelve years later, I got you right where I want you," Zach told a stunned Cheyenne. "And the best part about it is, this is right where I know you want to be too. Us making the decision to bring life into this world right here was the best decision we could ever make. I know you're going to be a great mother to Ace, and I'm going to be the best father I can be. I promise you that."

He continued: "But I feel we owe it to ourselves to now tie the knot and make our commitment for a lifetime."

And then he opened the ring box.

"Oh my God, it's huge!" a teary Chey exclaimed before Zach posed, "Cheyenne, will you marry me?"

Cheyenne happily accepted -- and then it was time for Zach to speak to Ryder and present her with an "exact replica" of her mom's sparkler.

"I just gave your mommy a ring, right?" Zach sweetly told the four-year-old. "That's a promise to be with her for the rest of her life. So this is my promise to you that I'll always be there for you, okay?"

Ryder sweetly embraced Zach, he picked her up and the trio shared a big hug. And no, we can't get enough of Ry posing with her new jewelry.

Congrats to the future Teen Mom OG husband and wife! Be sure to keep watching Cheyenne, Zach and Ryder as they prepare for Ace's arrival every Tuesday at 8/7c.