I guess I was a bit vague in my original post.

Me and a friend are flying from England to Brazil. She's from Brazil and is returning to her home country, i'm from England and I will be flying with her but only for a 4 week vacation. So I will use both parts of the return ticket, whilst she would only use the first part.

We are looking at American Airlines or Lufthansa. Both offer round-trip tickets at a cheaper price than single. But I don't want my friend to end up with a penalty fine for not completing her journey as she will be staying in Brazil.

Thanks for your fast replies by the way guys