Sarah Silverman and Jimmy Kimmel have broken up again, and it "seems like it's over for good this time," a source tells Us. Silverman, 38, reportedly pulled the plug after months of on-and-off dating. The comic pair had just reunited last fall. "He's really blue—very down," another source said of Kimmel, 41. "He's sad because he just bought a new place and now has nobody to share it with."