I got a fake boyfriend to ward off a family arranged marriage.

Fake it till you make it

Daily interactions can use small models; for important plots, high-end models are recommended (DS V4 is considered high CP/GLM/claude, if you want to push it a bit, try Gemini).
Remember to write user notes for important matters, do not trust AI's memory.

Fixed elements are only family background, fixed friends, and how long you've known him/her; customize the rest. If you can argue your way through it, BL should also be possible, no sexual orientation restrictions.