The definition of lead someone on is:
(phrasal verb) to trick someone, to mislead someone, to lie to someone
The beautiful girl led me on at the nightclub. She pretended she was interested in me, but when I asked her for a phone number, she told me to go away!
A: How was your date?
B: It was great, but he didn’t call me back yet!
A: When was it?
B: Three weeks ago.
A: I think he’s leading you on. Forget about him!
When we were planning a vacation, the advertisements led us on about how great the hotel was. When we arrived, it was horrible!