Shawn Mendes is spending his 21st birthday with rumored girlfriend Camila Cabello.

The "Senorita" collaborators, who have been fueling romance rumors all summer, were spotted leaving the restaurant Jack's Wife Freda in New York City on Thursday (August 8). Not only were they holding hands again, but the two were all smiles. TMZ cameras caught up with them and asked the Canadian singer how he plans to celebrate his big day. His reply? A request to let him and Cabello walk down the street in peace.

At one point, the cameraman asks Cabello what she got Mendes for his birthday, but she doesn't reply.

Check out the TMZ clip, below:

Fans also spotted the pop stars walking the streets of NYC on Wednesday (August 7). In a video posted to Twitter, you can see the former Fifth Harmony singer adorably pulling Mendes towards her.

Though neither has confirmed their relationship status, the pair have been packing on the PDA everywhere they go. Earlier this week, Cabello also opened up how much Mendes means to her, telling Variety, “I’ve known Shawn for such a long time and it’s so much fun getting to work and do things with somebody who means a lot to you.”

She also discussed her upcoming album and revealed she wrote it while she was "falling in love." Though she might be referring to ex Matthew Hussey, whom she broke up with in June, she described the feeling as "an infinite amount of levels and layers and angles," adding that she "fell in love and just opened up."

Whoever the album is about, it certainly seems like she and Mendes have fallen for each other. In fact, sources say their relationship is "moving quickly" because the timing is finally right for them.

"It already feels to them like they've been together for a lot longer than they have," an insider told E! News. "They've known each other and been a part of each other's lives for a while so it's all very natural and moving quickly."