After the one ring was destroyed and Aragorn was crowned King of Gondor and Arnor, he and Arwen were married. Though he looks older than his bride, I'm learning that Arwen is actually older than Aragorn by at least 2,600 years. She's obviously robbing the cradle, but I can't get an exact fix on exactly how old they were when married.
Both Aragorn and Arwen's births, and their marriage, are listed in the Third Age section of The Tale of Years (Appendix B, at the back of Return of the King). Arwen was born in the year 241. Aragorn was born on March 1 of 2931. Since they were married at the end of June in 3019, this means Aragorn was 88 years old when they were married, and Arwen was either 2778 or 2777 (depending on whether she was born in the first or second half of the year).