I have a roundtrip ticket for an upcoming vacation, but have decided now to ride out with friends and just fly home. Will the airline cancel the return flight when I don’t show up for the outbound flight, and if so, is there any way to prevent this?

Many years ago it was a simple matter of calling the airline and politely asking them not to cancel the return. Today is a different story. Now if you do not show up for the outbound flight the airline automatically cancels the return. If you still want to use the return it is necessary to cancel the outbound flight before departure time and have the roundtrip ticket exchanged for a one-way ticket. On a case-by-case basis the airline may make an exception to this if the reason you didn’t take the outbound flight is directly related to airline performance. For example, if your outbound flight was delayed and there were no alternatives to get you to your destination faster than you could drive it. Do not expect an exception to be granted if you are held up from arriving at the airport on time due to traffic or construction, or security lines are slower than you allowed for.