There are many of them. Picture a couple who speak different love languages. For the purpose of the example this couple will consist of a man and a woman. So one of his love languages has to do with food. When she cooks a good meal for him he knows that she loves him. However, her love language is being taken out for dinner. So if he doesn't know that this is her love language, then no matter how much he demonstrates appreciation for the meals she prepares, she is not going to feel loved because he has not taken her out. And he is probably thinking to himself,"Why go out and waste that money when I eat better right here at home?" So then he takes her out for a meal, eventually, and she enjoys the meal but feels that there is pressure to "perform" afterwards. She already knows that one of his love languages is physical connection. That is excellent when this is a love language for both people. But if it is not so much for her, then there is another stumbling block in the relationship.
It is amazing how complicated people make their relationships. When it all comes down to the nitty gritty of it all, if you know your partner's love language, then speak it. This is a person that you love and trust and if you are not willing to speak the love language, then you are not really loving that person in a demonstrative way. So cook, clean, take out to dinner, make love and do everything that you can to connect in a loving way with each other. The relationship will flourish when both parties do this. If you don't know your partner's love language, find out what it is. Love language is easy to learn. Then all you have to do is respond to it.