chicken out on
chicken out on (one)
To impact someone else with one's refusal to do something due to fear (real or perceived). We've come this far. Don't chicken out on me now—I need you to help me climb the rest of the way!
chicken out on someone
Inf. to decide not to do something for or with someone. Come on, don't chicken out on me now! Ken chickened out on us and won't be going with us.