http://www.mangago.me/read-manga/long_vacation/
I'm not too sure if this is it or not, but it does match the description in a way. If it's not it, I hope you find it some day, cause I'd like to read it too. (=・ω・=)
Well i know one ..
http://www.mangago.me/read-manga/venus_wa_kataomoi/
i hope it helps
This one hasn't had an update in a little while :( I think the plot is headed towards girl falling in love with gay guy.
http://www.mangago.me/read-manga/that_summer_kim_hyun/
Can u guys tell me any manga with a plot of "girl and gay guy" romance?
Of course in the end the girl and the guy must got together, I've once read one of it already, though I forgot the title.
Thanks!