Marie doesn't go out with them socially because she doesn't like it.
She knows she will have to perform for the camera and has previously stated it is 'hard' constantly performing.
I think she was unimpressed with Stephanie's cake, not so much because it tasted awful but because Stephanie was mocking something that Marie liked.
Stephanie’s cake was not made with love, it was made with derision. I believe that is why Marie was not enamored of Stephanie’s efforts to bake a cake for her birthday. Marie also knows that Stephanie would never have baked her cake if she were not filming and exploiting Marie‘s birthday for content for the CD channel from which only Stephanie profits. Marie has essentially given up her YouTube channel to take the job as they cook, and jack of all trades inside the dump for the next two years. Although Marie was very well aware that she would be required to perform for the cameras to earn money for her salary and to personally enrich the gruesome twosome, Stephanie’s lack of content has led Stephanie to make Marie a recurring main character in many dump videos. In addition to taking care of the dog, cooking, cleaning the kitchen, doing the flowers, lighting, fires, and doing all sorts of additional duties at the dump, now she has to act and perform for a little pink camera at a moments notice.
The entire birthday video was scripted beforehand. Marie had to watch the gruesome twosome Suddenly fake concern for her welfare and take great efforts to come up with “ excuses” to get Marie to reluctantly take a day off from work And for the gruesome twosome, to look like they work in the kitchen and help clear tables.
It was all bullshit and damage control for the gruesome twosome, and really had nothing to do with Marie and her birthday and Marie knows it. Just another insincere and disingenuous day at the dump. Rinse and repeat.