One Word

It comes without warning

Yet may leave just as fast

It will linger

If you fight

--

It has no meaning

Yet you may have your own

It can be foolish

If you misunderstand

--

It can be weak

Yet also strong

It may not last

If you are blinded

--

It will be difficult

Yet you may like what you get

It has no ending

If only a beginning

--

It is called different things

Yet they all have the same concept

It can be simple as well as sweet