What the reason it may be
Never ever end it through a third party eg sms, email, courier,
letter, a mutual friend.
Be upfront about it and shorten the pain.
Excuses
We are not compatible.
Is there such thing as 100% compatibility? Can anyone accept
less?
We have too much differences.
Is there such things as opposite attracts?
You bored me.
How does one excite the other always?
You arent the man/women I fell in love with.
Ask yourself who you actually fell in love with and how much has
the person changed?
Changes are part and parcel of life. The only way a person can
remain unchanged is that he/she is dead.
Some changes are beyond our control and some are not. Being unable
to adapt to the changes is not an excuse to end the relationship.
Unless the person change for the worst.
"No reason." is an cowardly excuse.