Can anyone help me explain why both are acceptable, what the difference (if any) is between their usage? This came up in a discussion with my students today. The example sentence was "I could stay here for ever". My logic was that if refering to "I could stay here for....." a certain amount of time, then "ever" would be used as a separate word. If using the word "forever " as one specifc point in time, the two words should be combined. I'm not sure if there is something else to consider. Any comments? Ideas? Thanks.