sweet on

(idiomatic) Enamored with; fond of.

Example: 1874, Wilkie Collins, The Dead Alive, ch. 9:
  Silas had said, "John Jago is too sweet on Naomi not to come back."
1917, Zane Grey, Wildfire, ch. 14:
  "Yes, I Am sweet on Lucy, an' she won't have me," said Slone, steadily. "I asked her to let me come to you an' tell you I wanted to marry her."
2000 July 19, Tony Karon, "Drug Companies Are Supposed to Profit From Human Suffering," Time:
  And they behave as corporations are supposed to do, maximizing their profits . . . and pumping money into the political process to keep Washington sweet on their interests.'
2007, P. M. Carlson, "Frightened Out of Fear" in Sisters on the Case, Sara Paretsky (ed.), ISBN 9781440620331, p. 26 (Google preview):
  "Officer Degan is sweet on Johanna. I expect wedding bells any day."