In Trails into Reverie, Nadia is an insanely cute girl who talks in a super slangy (gyaru-ish?) fashion. She's obviously in love with her big-brother figure Swin (whom she calls "su-chan"). Anyways, when she tells Swin she's tired and to carry her, Swin doesn't have it and tells her to walk herself. In response, Nadia drops her shoulders and says "今日も冷たいすーちゃんでした。まる。" Anyways, the meaning is pretty obvious, but I'm not sure of the "maru" slang at the end. I know "まるで", but I'm not sure it particularly applies here. Which leads me to think it's some sort of slang I'm unaware of? Can anyone provide any insight?
It is a reading of '。', the proper full width period. So it is kind of like saying in English '..., period'. Saying まる just indicates the end of the sentence unlike English where 'period' sounds like emphasizing the statement (I may be mistaken).