John Mayer hasn't had the best track record with women in the past (see: Taylor Swift, Jennifer Aniston, and Jessica Simpson), but his future with girlfriend Katy Perry is looking brighter every day. The couple of 15 months (with a three-month break earlier this year) are fully committed and headed for an engagement, sources reveal in the Oct. 28 issue of Us Weekly.

"Everyone knows it's just a question of when John will propose," a source tells Us of the "Paper Doll" singer, 36, who took Perry, 29, as his date to his brother Carl's wedding at New York's Mamaroneck Beach & Yacht Club on Oct. 13. 

They "realize they must be together," the pal says. Adds another source: "They Skype and text all day. John always checks in before bed!"

For more on the couple's relationship -- including the "Roar" singer's sweet wedding interaction with her beau's 86-year-old dad, Richard -- watch this week's Hot Stuff video, as explained by Us Weekly entertainment director Ian Drew and American Idol season five winner Taylor Hicks, who has a recipe in Taste of Home's new cookbook Recipes Across America.

Other stories in the roundup: James Franco's gesture for a heartbroken fan; Nina Dobrev's split from Derek Hough; and much more!