A controlling partner gets mad at you for talking to someone of the opposite sex, even if the conversation is harmless, even if the conversation is short, even if you are completely platonic and have never even looked at each other in a sexual way.
A controlling partner gets frustrated when your attention is on someone other than them. They will be annoyed with your parents, your siblings, and your best friends for taking you away from them for even one weekend. They will see everyone else as competition. They will want you to love them more than your family, more than your pets, more than your childhood friends. They will aim to become the center of your universe, your only reason for breathing.
A controlling partner will make you feel like you need to ask for permission before doing anything. They will expect you to talk to them before you agree to hang out with your friends or agree to overtime at work. They will make you feel guilty, like you have done something unspeakably wrong, whenever you see a certain movie without them or try a new restaurant without them. They will aim to isolate you. They will be happiest when you are alone in the house, because if they cannot be with you, they don’t want anybody else with you either.
A controlling partner will need to know where you are at all times — but hearing your answer will not be enough. They will want evidence. They will ask for photographs. They will call your office. They will text twenty times in a row to make sure you are telling the truth.
A controlling partner will act like you owe them something. They will bring up all the ways you hurt them in the past in order to make you feel like you have to work extra hard for their love. Whenever you make the tiniest mistake, they will act like it is the end of the world. They will trivialize their own errors and emphasize yours to make it seem like you are lucky they put up with you.
A controlling partner will make all the decisions in the relationship. They will decide what you watch and what you eat and how you spend your weekends. They will hold all of the power. During the rare instances when they ask you to pick something, your choice will only be an illusion, because they will manipulate you into choosing what they want.
A controlling partner will give subtle insults they can pass off as harmless jokes. They will comment on how unattractive your outfits are so you will dress differently. They will comment on how soft your stomach is so you will work out more. They will comment on how flaky your friends are so you will grow distant from them.
A controlling partner will make you feel horrible about yourself. They will heighten your insecurities. They will tire you out, spiritually and emotionally, until you come to your senses and realize you deserve better.