besotted with

in love with

head over heels about

obsessed with

taken with

lovesick for

moonstruck over

enamored of

attracted to

devoted to

captivated by

enthralled by

enchanted by

bewitched by

under the spell of

smitten with

sweet on

keen on

hot for

gone on

hung up on

mad about

crazy about

nuts about

stuck on

carrying a torch for