How do you tell someone that you like them even if they have a girlfriend?

there are plenty of ways to let a guy know you like them with out actually saying anything. be creative and smile and be his good friend- if you really like him then you should care about him and be genuinely interested in him and how he is doing regaurdless of who he is with- at some point- it is almost a certainty that he will not be with his gf- and he may remember how good you made him feel about himself and then come around