You shouldn't back out of commitments you make.
Greg promised Janet a beautiful evening out when his friend Jose asks him to go shoot some pool.
Greg wants to respond to Jose's request.
Greg tells Jose that he already promised Janet a lovely night out, so he will have to take a rain-check.
Greg tells Janet last minute that he decided to go play some pool with Jose, and they can just go out another night.
Janet is thrilled that Greg chose her over Jose and has a beautiful time.
Janet's feelings are hurt, and she doesn't trust Greg any longer.