Sometimes major events like the death of a family member or significant barriers like the loss of a hard drive/computer give the time to look back at what you've been doing and re-evaluate. Perhaps they did intend to return but it was just not worth redoing all of that work, or on reflection you were pouring yourself into the work for incommensurate reward, or it was just too hard and you didn't know what to do so it was easier to just stop.