I had a look and it appears you indeed found a bug - once you buy the wrong running outfit the part where you give her the present will repeat every time you enter the lounge. It will also not trigger the feedback from the studio, so you can't progress.
You can do I of 2 things (I recommend doing both):
1. Restart the game and when prompted to buy the running outfit the 1st time, buy the right most one in a medium.
2. Post the save and description of the problem on the dev's discord at
You must be registered to see the links
in the #help-section. He is a lot more on his discord than here on F95.