By remembering that they're just ordinary people - the same as you and me. The only difference is who they are sexually attracted to. And that doesn't concern you in the slightest.
They have homes, jobs, friends, hobbies, loves and hates, wishes, families - all the usual things.
And if it's the sex part that bothers you, just remind yourself that they don't do anything that straight couples don't do.
The only reason anyone has a problem with homosexuality is because people have been brainwashed by the Bible. And if you think about it, what does it matter what an ancient book of legends says?