Sheryl Sandberg, Facebook’s chief operating officer, announced her engagement to Tom Bernthal, the founder of a Los Angeles-based strategic consulting agency, on Monday.

“Engaged!!! Tom Bernthal, you are my everything. I could not love you more,” Ms. Sandberg, 50, said in a Facebook post.

Mr. Bernthal replied in a comment: “Sheryl Sandberg, I love you so much and couldn’t be more excited about spending the rest of our lives together.”

The couple, set up by Ms. Sandberg’s former brother-in-law, were engaged over the weekend, People reported. Ms. Sandberg has two children, and Mr. Bernthal has three.