He shares few details -- we don't even know his lucky lady's name! -- but it's clear the couple has a sense of humor when it comes to adventures. While talking to Leno, Lucas revealed a bizarre story about staying in a hilltop trailer in Big Sur, Calif. -- an "eco-retreat" that had his girlfriend terrified.
Long story short, after a close call with a mountain lion on a cliffside, Lucas realized his girl was officially "the one."
Congrats to Lucas and his new fiancee! Check out the actor talking about their adventure with Leno above, and photos of other celebrity couples below.