Why do Long-Term Realtionships End in so much heartbreak?

Because each party is too afraid to let go before the person moves away. Some long term relationships work, but soon enough they eventually fall apart, Heartbreak is a part of saying it's the end. Would you rather continue with a relationship where you're unsure and unhappy, or, suffer a little heartbreak?

Because you have gotten used to the fact that your in a relationship. Your used to the fact that their is always that special someone that you can go to when your hurt. In a short term relationship, your not as used to that person being with you. In a long term, your used to the fact that someone is their by your side. It can also depend on the way that it ended. If the person was cheating on you, then you feel as if the person you thought you knew is gone. If you can't see a reason, you begin to wonder what's wrong with you, if anything.

Because you have had so much time to get to know a person and then they leave and it is kind of like a change of life and that is never really easy to do. I most cases it is good thing in the long run but in order to turn good it usually starts out bad

well he sounds like a jerk to me.. 1st he sleeps with you right after he breaks up with his LONG TERM gf, if it was long term he should be atleast feeling sad and not wanting to sleep with anyone. then he says he wants to work it out with the girl while playing with your feelings and saying that he fancies you.. (kinda cheating on her too really) so ok, maybe you still like him.. but even if you guys went out, he seems like the type that would hurt you to no end (even more than he is hurting you now) so just leave him and his gf (they'll break up soon anyways with the kind of guy he is) and go concentrate on something else -notice how i didnt say someone- until you dont like him anymore and THEN go for somone else!

Because people expect way too much out of long-term relationships. It's easier to stay single and know exactly what to expect.

Addiction. There is medical evidence that when you fall in love, it is like a drug in that you feel super euphoric at first, then you become used to it and it doesn't seem like a big deal. However, when you take away the love, your "drug", you literally go through withdrawals and you feel depressed. Luckily, the feeling always passes with time...

Because Long-Term relationships mean long-term FEELINGS, and having those ripped out and stomped on doesn't make you feel like dancing.

b/cuz the 2 arent usually ready they think they love eachother but they really dont kno eachother that well theyre just 2 eager 2 get in2 the relationship

Someone usually ends of messing up. Or communication gets messed up and you both just go your separate ways for no reasons.

Because so much time/effort/emotion/love has been invested without an end product.

It's gonna hurt, baby.