The couple have sealed their love by getting engaged after dating for just three months, a rep for Kaley told Us Weekly.
It is believed that tennis ace Ryan, 26, proposed on Wednesday (25 September) just days after the couple made their red carpet debut at a pre-Emmys party and at the Primetime Emmy Awards.
There was speculation that Ryan had popped the question this week when Kaley, 27, flashed a diamond ring while on the set of her film The Wedding Ringer.
But despite their whirlwind romance, it seems like the couple are head-over-heels for one another. A source told the publication that Ryan is "The One".
Kaley hinted at her joy on Wednesday, when she told her 1.6 million Twitter followers: "Flying high, I could literally touch the sky with you..." At the Emmy party last week, a loved-up Kaley posted a cute photo of the pair to Instagram, calling Ryan the "greatest date ever".
Prior to Ryan, Kaley briefly dated Man of Steel actor Henry Cavill.
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Copyright: Instagram Mark Wright