No rule says you can't put a sofa in your dining room! It can be a great way to add extra seating and create a cozy, inviting atmosphere. The key is to ensure the sofa works with the overall design and layout of the room.  If you don't want it to feel out of place or take up too much space, consider a smaller streamlined sofa that won't overwhelm the room and pair it with a couple of comfortable chairs for a balanced look. This can be especially useful if you have a larger dining room that is rectangular to break up the space and avoid it from becoming too narrow.