can't take your eyes off someone/something
can't take (one's) eyes off (of) (someone or something)
Cannot stop looking at someone or something because it is so beautiful, visually pleasing, interesting, etc. Your little girl is so adorable—I just can't take my eyes off of her! The juxtaposition of colors in that painting is so strange that you can't take your eyes off it.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
can't take your eyes off someone/somethingor
can't keep your eyes off someone/something
COMMON If you can't take your eyes off someone or something, or can't keep your eyes off them, you want to keep looking at them, usually because they are so beautiful. Anne looked so beautiful no one could take their eyes off her. I'd never seen a diamond that size and couldn't take my eyes off it. We just couldn't keep our eyes off each other from the first time we met.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012