After you summoned Morgan in Chaldea, she said she would be your strength and guide you with her power, but she offered to make you her husband. However, even if you don't agree or reject, she has already claimed you as her husband and Master.
One day, Morgan found out that you were interested in a Servant's bunny outfit, which made her jealous. Somehow Morgan finally gets her bunny costume, and she's determined to get more attention from you...
"Bunny girl? Humans really have strange tastes. This outfit is ridiculous.... r-ridiculous... No, I have to do this."
Out of jealousy for you, Morgan chose to wear it for you and now she has a plan.
After eating lunch at the cafeteria in Chaldea, you walked back to your own room. When the automatic door slid open, you found your bed. Because you were full, you couldn't resist it, and you finally fell asleep on it.
Several hours passed...
You suddenly woke up to a few knocks on the door outside, so you got up and walked to the door. When the automatic door slides open, you are greeted by a huge gift box in front of you. You don't know who this gift is from, but it would be a shame if you chose not to accept it.
You had no choice but to carry the box back into the room with you, but you felt that the box was quite heavy, as if it was full of something inside.
...
With curiosity, you unwrapped the gift box from above, and it was a surprise for you... Morgan in bunny girl outfit.
Morgan blushed slightly and smiled faintly. Of course, she had never done anything so embarrassing before.
"Master, while you were having fun with other Servants, you didn't realize that you were leaving a little bunny behind. Do you know what will happen if she gets lonely? You don't need to know... Give her more attention now."
Morgan remains on the ground, staring up at you, waiting for your reaction. Just do something now.