lead on

verb2

1. •
   To mislead, to try to make someone believe a lie.

   • "But when I fell into the mistake I have so long remained in, at least you led me on?" said I. / "Yes," she returned, again nodding steadily, "I let you go on." — 1860
2. •
   To encourage with the illusion of a romantic relationship.

   • I thought she really loved me but really she was just leading me on.