'Forever' means for an infinite length of time. 'Always' means at all times. 'Ever' is a question word (and is also used in negative sentences); it has no time value.

It can be viewed that "for ever" and "always" are the same. For example a tipical situation when you confess your boyfriend that you love him: I will love you for ever. or I will always love you. So in the first example the verb is going to be before the "for ever" and at the second example it will be after. However "for ever" is a bit more romantic, because loving someone until end of the world and then loving him after that as well is something imposible if we study "for ever" word by word.