Blended families come with change; one minute it’s you and your immediate family, next minute this immediate family expands to a new set of people. Now all of a sudden, you might have to share a room and sometimes even outfits. It could be a bit uncomfortable, even for the most accommodating person.
This poster had to deal with one of these changes when her stepsister got pregnant and her parents expected her to be accommodating even though she already was. This kept going on until she reached her breaking point – asking to move out.
More info: Reddit
