@ChronicLogic It means FL will return to the inn even after 2 years (The girl smiling at end is the one who did the intern 2 years ago as seen in the first 2 pages) AKA she may look like she escaped or whatever but will eventually cheat.
@ChronicLogic I don't quite agree with KankoNitta's assessment. All the ending implies is that the previous girl that interned at this company, the senpai at the beginning of the story, is still likely working for the company. She knew what the FL was going to go through and still sent her there. While its reasonable to assume FL is addicted to Saejima's cock and would probably come back, the ending doesn't imply that.