(1) A favored male romantic companion with whom no commitment nor title has yet been established. While a committed relationship is expected to be eminent, specific elements prevent this from occurring (distance, parental demands, awaiting divorce finalization, or simple "not-to-that-point-yet" reasoning.) While no commitment has been made, and you are free to date others, feelings for said partner often prevent it. Your non-boyfriend is often unaware that you have dubbed him as such, but all of your friends are aware of it. This relationship phase will fall somewhere between "Boyfriend" and "That-guy-I've-been-seeing".
(2) A fuck buddy with whom emotional feelings are present and mutual, but not discussed and no commitment exists.
Beth: So what's the deal with you and Mark? Is he your boyfriend or are you guys just friends?
Ashley: We haven't really talked about it yet, but we'll have our 5th date tomorrow. He's definitely more my non-boyfriend.