Originally Posted by
moondog
Without looking at the OP's tickets, how can you be so sure? It's possible, though admittedly not likely, that Expedia sold the OP two separate tickets and subsequently linked them. If so, severing the link could be a simple matter.
Interestingly, the only time I bought a RT ticket from Expedia (the $300-off coupon at the end of last year), I skipped the outbound flight but the return ticket was still good. So maybe there's some quirk in their booking system that sometimes allows this. However, I wouldn't risk it, especially for an international trip.