somehow when i'm reading this, in my mind saying that's simply a gemini.... that's a natural attitude for them since they have short attention span and indecisive.
first of all, maybe he's got a problem that he needs to go through. or maybe he got bored and explains why he's there but the effort is not like what he used to give before. or simply, he doesn't think that's it's a big deal just like how you think of it..... (yeah... gemini have a simple mind set.... don't be surprised that it's waaayyyy different than water signs mind set)
lol, i understand that clingy and needy part... i'm a scorpio after all :p
and that "maybe" i listed up there is what exactly happened in my experience with my man (yeah, he's a gemini). i used to take it overboard and makes small things bigger and that's simply drives him mad though (i still can't understand how he calmed down and stayed with me........... i need to respect him on that~~)
anyway, just don't think it too deep. let him free though..... because for a gemini, i believe that if he comes back after you set him free than he is yours after all. don't worry either he will cheat with girls, he might get bored of you or he might not like you at all by the way he act.... gemini is simple, they will tell if they're getting bored or meeting new girls or whatever.
for you... just be a cool girl! hahaha don't let too much emotions control you. and ypu need to be very patient since well..... gemini is indecisive ~~~ slowly though, you can adapt with gemini's style.... ;)