John Mayer, Katy Perry To Wed? 'Just A Question Of When'

John Mayer and Katy Perry's relationship survived a rocky start, and today, the pair is sparking rumors of an engagement.

Over the weekend, the couple was spotted in New York City where Perry served as the host of "Saturday Night Live's" Oct. 12 episode before she joined Mayer at his brother's wedding in Westchester, New York.

"Everyone knows it's just a question of when John will propose," said a friend of Mayer's, according to Us Weekly.

Also during the wedding festivities, Perry joined Mayer's 86-year-old father Richard on the dance floor and later provided top-shelf champagne for the wedding guests.

"[They] were beyond affectionate and adorable," another onlooker said of the couple, according to Us Weekly. "He was rubbing her back, then pulled her in for an intimate close chat. She put her hand inside his jacket and they were kissing and gazing into each others' eyes."

Furthering the marriage speculation, Perry put her love for Mayer on display with a special post to Twitter for Mayer's 35th birthday on Oct. 16.

"happy birthday cutie!!! @johnmayer," the singer wrote.

Mayer is currently on the European leg of his "Born and Raised" tour.

During a performance back in July, Mayer dedicated his song "A Face to Call Home" to Perry, citing his girlfriend as "so patient to continue to get to know me and love me" while he recovered from throat polyps.

Shedding more light on their romance, Perry referred to Mayer as a "genius" during an interview with Billboard magazine.

"I always tell him, 'Darling, you know I'm going to have to give your mind to science after you've passed, because we're going to have to understand how all these sparks work,'" she said.

Meanwhile, Perry will celebrate her 29th birthday on Oct. 28th this year, just days after her latest album "Prism" hits stores.

The "California Gurlz" singer began dating Mayer not long after her divorce from Russell Brand became final in Feb. 2012.

Alternately, Mayer is well known for having numerous past relationships, including those with Jennifer Aniston, Taylor Swift, and Jessica Simpson.