my 1 female guppy had a darker gravid spot for a wile without gaining wait, then today it like dissapeared. what happened?
also on a simi related topic my male refuses to leave that same female alone. will that stop?
If the male wont leave the female aone then, get more female guppies (you should have 1 male to every 3-4 females)
Gravid spots are very strange things, its not always a good thing to rely on them for pregnancy related issues, as the gravid spot can appear on un pregnant females and not appear on pregnant ones..
You said she did not gain weight, was she already fat though? (looked pregnant)
If so then it probably has dropped its fry and this been the reason wy the gravid spot has faded (this is what usually happens - but not all the time as stated above)
Another thing, When you first noticed the gravid spot had faded, had you just turned the fish tank light on? if so it will re appear after the light as been on a while, gravid spots to lighten in darkness and get darker when the lights back on