They only like to talk about themselves
If you're dating someone extremely self absorbed, your date night conversation will most likely revolve around his or her achievements, success, and interests.
"The narcissist will often appear bored when talking about you, or change the subject to focus on them," Beresin said. "Sometimes they are good listeners, but only when it enhances their own needs and desires."
They want you to provide them with constant praise
Narcissists always want to be the center of attention and will expect their S.O. to acknowledge their achievements, talents, and appearance at all times. (Yes, even when you are at a social get-together.)
According to Beresin, your relationship may suffer if you don't dote on him or her. They may take offense if you show any sign of disapproval, disagree with what they say, or if you question how great they are.
They are demeaning towards other people
Egocentrics often obsess over the negative aspects of other peoples lives. Even their close friends and family members may not be spared from the judgment. Narcissists often think they can do a better job than others, which reinforces the belief that they are always right.
They are sensitive and they overreact
When a narcissist's emotional needs aren't met, their reaction is often grandiose. According to Dr. Talley, many narcissistic people may appear extremely angry or cry until the other person apologizes.
They lack empathy
Your S.O. may offer to come over when you are having a bad day, but their motivation is most likely self-serving.
"When the world is all about you, there is little room left to have genuine and sustained empathy toward others," says Talley. "It seldom translates into action where they act in a way that requires sacrifice and humility.”
They make you feel bad about yourself
Don't expect a narcissistic boyfriend or girlfriend to be genuinely happy for you. Instead, they will most likely be overly critical or attempt to downplay your accomplishments.
"They will frequently cause you to feel badly about yourself. Your success threatens them, so you can expect that they will respond to your successes by ultimately diminishing their importance," says Talley.
They can be charming and generous ... sometimes
Narcissists have moments when they seem incredibly likeable, especially early in a relationship. "The narcissist can be charming and generous when it enhances their sense of how wonderful they are, but all this can turn in an instant to sulking or angrily lashing out when others do not respond as they expected," says Talley.
If it feels like everything switched after the "honeymoon period" it may be true. Narcissists "often make others feel special as they are welcomed into the their world, which is painted as being exclusive, exciting, filled with potential, and very special," Talley says. "But shortly after this initial stage they become dependent on the relationship and this dependency causes them to no longer be able to maintain the facade of genuinely caring for another."