You're a "dating expert" and you didn't see what was coming? Doubt it.

I love my friends, but I seriously doubt I would pay for their airfare, food and accommodations, especially if it was international travel. I doubt that they would accept it, unless I was fabulously rich (which I'm not). It would be weird...regardless of gender. I can't believe for a minute that you didn't consider that he might have ulterior motives. If not sexual, definitely romantic.

1. You knew he invited you as more than a friend, from the beginning.

2. You knew, based on his personality, that if things got weird, you could claim an innocent misunderstanding and you weren't going to be in any danger.

3. So you used him for free entertainment.

He was an idiot for expecting anything in return for funding the trip, but you used him. You took advantage of his very poor judgement.