Justin Bieber serenades fiancee Hailey Baldwin outside Buckingham Palace

Nothing charms a girl's heart like a public serenade!

Justin Bieber was spotted serenading his fiancee, Hailey Baldwin, outside of Buckingham Palace in London, England, on Tuesday. The pop star, dressed casually in black shorts and a pink-and-gray sweatshirt, hopped out of his and Baldwin's black SUV with his guitar, ran over to take a seat at the fountain and started playing his song, "Coldwater."

It didn't take long for a crowd to form around the couple, with fans taking to social media to post pics and videos of the cute moment. Some tweeted that Bieber was asking for song requests, while others were charmed by Baldwin's bashful reaction.

Bieber, 24, and Baldwin, 21, arrived in London earlier this week, where they've continued to pack on the PDA in the wake of reports they might already be married.

"I understand where the speculation is coming from, but I'm not married yet!" the model wrote in a since-deleted tweet last week.

A source told ET at the time that while Bieber and Baldwin did register for a marriage license, they did not have a marriage ceremony yet. The marriage license Bieber and Baldwin obtained became valid after 24 hours and remains valid for another 60 days anywhere in the state of New York. If they decide to tie the knot overseas, Bieber and Baldwin would have to have a civil service in the state first in order to make it legal.

See more photos of them together:


Justin Bieber and Hailey Baldwin Look More in Love Than Ever Amid Wedding Rumors

Hailey Baldwin Addresses Justin Bieber Wedding Rumors

Justin Bieber and Hailey Baldwin Register For Marriage License at NYC Courthouse