1) If the "lame petting" as Emiru puts it with Makiko counts as fucking, then I suppose Emiru is shown fucking two more people in the manga, namely, some similar petting with one other girl who "doesn't swing that way" and the coitus with Tatsuhiko (the MC) at the end.
It's heavily implied, if not outright confirmed, that Emiru remains...ahem...physically intact...until she goes all the way with Tatsuhiko. A much later key plot point after the two petting incidents involves Emiru opening her legs, spreading her "equipment" with her hands, and showing it at point blank range to Tatsuhiko's new girlfriend to prove that her "equipment" remains "unused" so Tatsuhiko can't possibly have fucked her. When Emiru and Tatsuhiko finally decides to go all the way, Tatsuhiko isn't able to penetrate her on the first try. While they take a short embarrassment break before trying again, Tatsuhiko laments that his partner is a virgin but he's the one acting more like the virgin. After they finally succeed in going all the way, Tatsuhiko worries that he may have hurt her (which, judging by the art, he almost certainly has, and not just a little).
2) Remember that this happens when Makiko confronts Emiru with suspicions that there is something going on between Emiru and Tatsuhiko that Emiru is trying to hide (Makiko isn't exactly wrong there). Given Emiru's modus operandi, she was probably trying to entrap Makiko by securing some blackmail material so that Makiko wouldn't take her suspicions to Yuri, Tatsuhiko's girlfriend at the time. This appeared to work, as Emiru and Makiko ended up agreeing to keep each other's secret. Emiru going to lewd lengths to protect Tatsuhiko is a running theme of the manga (such as the aforementioned incident of Emiru shoving her spread "equipment" in Tatsuhiko's new girlfriend's face to prove that Tatsuhiko hasn't fucked her).