first of all if you had a girlfriend and when you first meet a guy you tell them "i feel this way, i have a g/f, tell me now if you have a problem"
if your up front in the beginning you shouldn't have any problems.
it's possible that you can find someone that was okay with it, develop feelings for you, and not be okay with it any more.
it's so many guys who would love to be in that situation.