Moving in with one's romantic partner is a big step and involves a lot of rejiggering of roles and responsibilities for the new household to run smoothly.
Sometimes certain chores were done differently and now you need to compromise. Maybe one person prefers to budget down to the penny and the other prefers to just have "fun money" and leave the rest to budget itself.
Whatever the skills, preferences, or traditions each person brings with them, a new normal needs to be established through communication and understanding.