There are many kinds of love, but when one is talking about relationships and partners and marriages, that is long term relationships and significant others, well we are talking about intimacy not just love. Love or when one has a crush on somebody is just a physical attraction where strong chemicals such as Opiods are involved, they are very strong but they tend to last only a few months. After that you need more than physical attraction, including sexual attraction, intimacy which is more psychological and requires a certain maturity and good communication in order to last. I would say the natural thing is to fall out of love, but then intimacy through good communication, understanding of roles, and personal space should grow and should foster a deeper intimate spiritual close relationship that beats love.

Death. When they're gone, they're gone and not coming back. Celebrate the relationship. Remember the good times then move on. Fall in love again.

Sticking ya dick into someone else is a common reason

did you ever see the movie "The Serpent and the Rainbow"? This journalist wanted to learn the secret to the myths of how people were made into zombies in Haiti. But he found out far too late that the only way to truly understand was to go through it.

So, with that in mind, I would wish that you never truly have to know the answer to your question.

Probably boredom.

I think the same question can be asked as to why people fall IN love... love isn’t a tangible thing, you can’t see it or hold it or even explain it to anyone else when you feel it. So what is it? Some singer laments that the opposite of love isn’t hate, it’s apathy... I suppose scientifically we just start to ignore the attractive force of a partner’s pheremones and mentally focus more on their flaws and faults.

I don't think anyone can answer that. We change. Our relationships change. Everything changes, We don't have the same helpless, worship, love for our parents at 10 that we have at two.

Not likely.
Probably can't explain why it works so well with people either... but if it is why are you wasting time thinking about it and analyzing it. Just be present in that moment as much as possible.

It's interesting to read these comments. I haven't really fallen out of love with anyone. Sometimes people die, and sometimes you need to move on for all sorts of reasons. The reason for the end of my last relationship was that I found out that he was someone completely different than the person that he had pretended to be.