According to this report, GMU has 4250 international students on its main campuses, and its facts and figures page says it has 39763 students on its main campus overall. So the probability a random GMU student (if I model Decker's eventual partner as such) is international is about 4250/39763 = 11%. That's assuming he decides to even date at all rather than focusing on something else (like X shitposting or grad school, and also he's bi which might skew the numbers somewhat) and that he mainly stays within GMU though.