Why does my partner not get me?  Why can’t he or she read my mind?

I hear you! And, let me tell you that you are not alone or wrong to think this way. This frustration can be rooted back in the communication styles that exist between couples.
If you are an inferential communicator, you will drop subtle clues or try to skirt the issue so as to not come off too direct or sound harsh. You may also want your partner to read your clues and understand what you want. But, if your partner is a literal listener, he or she may not get what you want them to get.
Flip the scenario, if you have a literal communicator and an inferential listener, again the message is lost.
So, here is my advice to you, if your partner likes it directly, give it to them directly. The goal is to communicate and not read minds.

Similarly, if you know your partner says it like it is, don’t take offence. Instead, take the message at face value and move on.

Specifically to communicate better if you have conflicting styles try these simple yet effective tips.
Ask questions:
Don’t be afraid to ask. It is always better to ask than to assume. It shows to your partner that you are making an active effort.
Communicate often:
The more you communicate, the more you learn. Remember, any relationship takes work and when you put in the effort, you will nourish your relationship resulting in fewer conflicts.
Life is complicated enough, let us keep our communication simple!