What does putting yourself on the line mean?

Source:

For my generation, friendship often morphs into a sexual encounter and then reverts to friendship the next day. And it’s easy as long as you don’t put yourself on the line or try too hard. Don’t have a prospect? Check Facebook. Afraid to call? Text.

(New York Times)

Probably taking things a bit too seriously? Making it a life-or-death situation (you know what I mean)?

Well, putting your life on the line means risking your life, so I guess putting yourself on the line means that you're staking a lot on something.

"I'm putting my job on the line to recommend you for a promotion." This would mean that I risk being fired if you screw up. Putting something "on the line" means