Wants are free-standing desires. You want whatever you want. The word "need" is always associated with an "in order to." For example, you only need air in order to continue living.

It is valid to use the word "need" to refer to something that you must get from your partner in order for you to be happy being married to them. With respect to things in this category, it is important to refer to them as "needs," rather than as mere "wants." A partner does not have to give you what you need, but you also don't need to stay married to them.