Once bitten, twice shy

Definitions:
CD: said when you are frightened to do something again because you had an unpleasant experience doing it the first time
CL: to indicate that someone will not do something a second time because they had a bad experience the first time they did it.
UD: orignally to dog bites, now means that once somebody has gotten hurt or had something go wrong will be afraid to try it again (especially in love). If you fall in love with someone and that someone rejects or hurts you-once bitten-you may be very, very reluctant-twice shy-to let yourself fall in love again.
MW: used to mean that a person who has failed or been hurt when trying to do something is careful or fearful about doing it again
MD: used for saying that someone will be careful about doing something again, or will be unwilling to do it again because they failed or were hurt the first time they did it

Examples:
- Elle was once bitten twice shy since her last relationship.