I wouldn't worry about him leaving for Seattle. You slept with a friend once and things were never the same. You're supposed to learn from your mistakes. If this friendship is too valuable to risk, then don't risk it. There's a time and a place for everything.
Good friends are hard to find.
Keep in touch and some day the two of you might have a future together and maybe even some sex in Seattle, too. Me Harlan is the property of the column. Any reproduction or distribution without prior consent is prohibited.