Is your desire to be in a relationship worth dating a narcissist? One relationship expert says don't even bother.

FOX's Ashley Papa reports:

Sometimes we fall in love so fast, we miss signs that show our date may not be a good person, after all. This is especially common with narcissists, says Dr. Ramani Durvasula, author of "Should I Stay or Should I Go?"

It can even take months to realize you've fallen for a narcissist:

(Dr. Durvasula) "People as a rule don't change that much and if red flags are showing up early, that's a bad sign, and I think sadly the message a lot of people get is 'well if I love somebody enough then they'll turn around' or 'if I'm really sweet to them, they'll be sweet to me.'"

By then, Durvasula says it's too late, because you're already sucked in. Try and change them, you'll end up wasting your time:

(Dr. Durvasula) "You might be able to train the narcissist to show up on time, but even if they show up on time they're still not going to listen to you. So it's very hard to change the fundamental core of the narcissist largely because they think everything's just fine, there is no incentive for them to change."

Durvasula says pay attention to signs early, like they lie a lot and act entitled to avoid getting taken by a narcissist's charm.

With FOX on Love, I'm Ashley Papa.

Follow Ashley Papa on Twitter: @AshleyMPapa
Follow Dr. Durvasula on Twitter: @doctorramani