Paul published the video on his YouTube page Monday morning, giving fans a behind-the-scenes look at one of the most important moments of his entire life.

Of course, we knew 28-year-old Paul and 31-year-old Agdal got engaged last week ... but now Logan and Nina are sharing video of the actual proposal in Lake Como, Italy.

Paul popped the question after dinner ... as the couple was taking in the beautiful scenery.

"Nina, I love you so much," Logan said ... as he turned into a puddle.

"You are the love of my life. You are the girl of my dreams. I never thought I'd find you. I never want to let you go. I'm sorry I'm being such a 'p***y'" ... before dropping down to one knee.

"Will you marry me?"

"Yes!" ... the couple embraced, and there were more tears!

After the proposal, Logan and Nina had dinner with her parents ... where LP asked the rents if he could ask for their daughter's hand in marriage.

Sure, that's typically done before you actually ask ... but that's when Logan revealed the weather forecast forced him to move up the day he was going to ask for her hand in marriage.

Thankfully, Mom and Dad said yes (whew 😰).

Paul also showed the moment in May when he first saw the huge rock of a ring that he helped design ... and he was clearly blown away.

"Oh my God, it's perfect," LP said when he saw the ring ... adding "People don't talk about how stressful it is for dudes to pick out rings for their soon-to-be wife."

Logan also showed his brother Jake's reaction to the engagement ring (he was psyched for his bro!) ... as well as his mother's!

Bottom line, the proposal was perfect ... and now it's time to plan a wedding!