There you go. That's it in one sentence.

Clearly they don't care about their mate's feelings. I say go ruin someone else's life.

My guess would typically be because they are not getting what they want or need from the current relationship. My opinion is if that is the case you need to get out of it, if you have kids & are married it does make it more complicated though

Because they never knew the word "Contentment"

Yes true

It could be that their current relationship has gotten dull and it feels good to have someone to want you again or show you the attention that you don't get at home.

There are some crazy things(sexual in nature) that you can't do with your partner or are too ashamed to ask your partner to do with you. But you can do these activities with someone you don't love

Might be the same reason they cheat on tests, etc -so they don't have to do the work (of making a good relationship)

obviously it's complicated and it's a situational cases that defines the parties involved but generally monogamous relationships which can be great are generally pieced by convenience usually uneven participating and both people one foot in other on future. well people have different ideas, plans and lives and your partner at 22 isn't what 32 needs or whatever. plus most relationships aren't love mostly a collection of attraction, remember the spark once had then all the history which can have good and lots of nip picking. so cheating is the cowardly way to jist admit we don't work and separate.

People being in relationships for mostly physical reasons -then a lack of physical contact.

need attention and care

i totally agree with you that cheaters always have their reasons.. for me best thing to do is find reasons to cut off with unworhty person then move on.

I think you meant the spirit of sincerity

Let's use another word, as it seems your vocabulary is not that broad!! Why do people "betray" their significant other by getting involved with another!

Hmmm

just my personal thoughts
people dont take time to build friendships and get to know each other any more
they feel physical attraction, then jump in the sack. sex is a recreational past time..
not viewed as a bond. so when the mating gets routine and they start learning more about each other.. they learn things each either dont like, or find lacking in each other. so they start looking for that in others. what may have been glances twards others, while things were hot, become desires that drive you to want them. once you settle in. getting to know your mate in advance, and they you. can lead to learning those things. prior to the point and prevent the cheating before you get to that point.
but theres also, those that after several years, just loose interest in each other. and seek new excitement with others.
but what do I know?? I've never been married. and cheating was never the cause of any of my break ups.. usually that was caused by money.

Some, do it to feed their egos?
Some, they just simply love living with it?
Some,lack of satisfaction?

We don't exactly know the path they are heading to, to know the reasons why people do cheat.

i think reasons for cheating is deep rooted and it is different for every person. what I came to understand is when i cheat, it means that i want to lie about my situation so i can be accepted by others. this is cheating in general.

I do hope my first wife read all of these posts. Nay, she still wouldn't get it.

They cheat because they don’t have a heart and know nothing about loyalty

People cheat because when they don't get what they need from their partner but being patient with your partner brings faith and lost hope back