maybe, it's the fact that when you miss someone, or that a lonely or an upset feeling sets in, so do negative thoughts, which maybe make you question if it's jealousy,,maybe it's not lealousy..
and while on this topic,, just the fact of not knowing where you stand wether it be in a relationship etc,,, can have similar affects, it's our mood that will control these types of thought,,
always try to find direct resolution,, if not an immediate opportunity do something active, something that doesn't allow you to think, that will calm it down a bit