Deciding what to have for dinner can feel like enough of a task when you're just one person, but it only gets more complicated when you are cooking for two. Just because your partner seems to be your soulmate in other respects doesn't mean that they are going to have exactly the same idea about what makes a tasty meal. When you share a kitchen, it makes sense for only one of you to be cooking at a time, but that isn't always going to be easy.
When couples have diets or preferences that differ, the best option may be for them to cook separately. Contrary to popular belief, couples don't have to do everything together if they don't want to. However, some may take issue with this idea, particularly if they prefer for their partner to be doing all of the cooking. It requires them to take on a responsibility that they perhaps don't believe they need to take when they are in a relationship. They just think that everything should happen according to their preferences, even if that causes them issues with their partner.