Spontaneity
For many people, spontaneity is important in intimate relations—to desire and to be desired at the same time. The media also shows us that spontaneity is important; lust arises instantly for both partners. However, everyday reality is often different. Partners are not always in the mood at the same time and in the same way. Desire and lust work differently for each partner.
There is a distinction between spontaneous and responsive desire. Spontaneous desire means that your flame ignites quickly. Your partner comes out of the shower dressed in only a towel, and you feel turned on. For responsive desire, the flame needs time to ignite. You require time to switch off from the daily hassles and space to get into the mood. More erotic context is needed before your flame awakens. The underlying principles are the same, but for some, it feels spontaneous, and for others, it feels like a slow build-up. Both are very normal!
Spontaneous and responsive desire are on a continuum. As partners, you will find yourself in different places on this line. There is also a good chance that each of you will shift your place on the continuum during your life. While someone may experience more spontaneous desire at a younger age, they may become more responsive later, or vice versa. The circumstances in your life can also have an influence. If you are busy at work, have a young family or have other pressing responsibilities, you may experience more responsiveness. While on a relaxing holiday, on the other hand, you may become more spontaneous in your desires.
All of this is very normal, but it makes spontaneous desire a myth for most relationships. Instead of waiting for the magic moment, relying on good coordination and some planning is much better. Discover where each of you is on the line between spontaneous and responsive desire, and look for ways to create a good erotic context for both of you in which the flame can grow without pressure.
If you want to know more about this subject, I highly recommend Emily Nagoski's book Come as You Are. In it, recent scientific findings about desire and sexuality are explained in a very accessible and usable manner.