My love languages (in descending priority) are quality time, acts of service, receiving gifts, and physical touch with words of affirmation being a distant fifth. Engineer W's languages are physical touch, words of affirmation, acts of service, and quality time with receiving gifts in last place. As you can see, our top languages don't overlap much. Because we're most likely to express our love in the languages that we would like to receive from others, that can lead to occasional misunderstandings and feeling under-appreciated at times. For example, Engineer W always thanks me for doing chores around the house, and I couldn't understand why. By comparison, I never used to thank him since I didn't value words of affirmation myself. Now I try to pay more attention to these differences so that he always feels loved and appreciated.
When I think about it, the concept of different love languages is pretty intuitive and really extends beyond just couples. It's applicable to anyone you love, like family and friends. Using this framework has changed the way I understand my parents, especially my mom. Whenever I go to visit her, she always tries to give me gifts to bring back with me, and I usually make excuses about not having enough space in my bag. Now I realize that she's trying to show me how much she loves me, and I should just take those gifts to avoid hurting her feelings.
So this Valentine's Day, when you think about what to get the person/people you love, think about how they show their love for you, and show your own love for them using that same language.