The Romanian national airline company has a strange policy: if you book a round-trip and for some reason you want to use only the return trip, then you’ll find out that it’s not possible. Your ticket is cancelled the moment you missed your first trip of the ticket. In legalese, it sounds like that:

4. Coupon sequence and use
a) Carrier will honor flight coupons only in sequence from the place of departure as shown on the ticket. The ticket will not be honored and will lose its validity if all the coupons are not used in the sequence provided in the ticket.
In particular the ticket does not entitle the passenger to commence his journey at any of the specified stopover points if the first coupon for an international flight has not in fact been used for transportation.
Tarom’s Terms and Conditions

I don’t know if other airline companies have this policy, but this post is just a heads up – as I find this policy completely illogical. Since you paid for the both flights, I don’t see any rational reason why the company would cancel your second flight if you didn’t use the first one.