Don't take my word for it. Ask his girlfriend.
So: Michael Phelps has a girlfriend! Awww. His girlfriend's name is Sarah Herndon, and she's a 22-year-old waitress from California, and he met her when some club employees put her at his table. Awww². (Actually, hahahahaha of course.)
Here is Sarah Herndon. (Apparently she found time to take a photoshoot during their vacation? Is this required of famous peoples' new paramours? I don't know how this works.)
Source: Jeff Rayner/Coleman-Rayner
Source: Jeff Rayner/Coleman-Rayner
And here is the happy couple together, with a lobster.
Source: Jeff Rayner/Coleman-Rayner