In another life or a parallel universe
There exists a person at two-degrees of separation from me who happens to be non-trivially pretty. I have not had a conversation with this person, nor have I been in a situation where I could have had one.
Irreconcilable ideological (read: religious) differences destroy any desire of a relationship.
Dealbreaker. :-(
However, this does not prevent me from wondering about the hypothetical situation in which I walk up to this person and say:
"I can't see things working out, but maybe they will, in another birth or a parallel universe. Farewell, have a great life! :-)"
While I definitely intend it to be a compliment to her, it would be creepy, and I don't believe in reincarnation anyway.
I'm not sure about parallel universes though.