The 22-year-old pop star and Shawn both feature on the chart-topping single, but Camila struggles to enjoy performing the track when her boyfriend isn't alongside her.
She shared: "It's lonely. I don't like it. I want him back. But it's fun. The fans sing it, and it's cool."
Camila recently released her second solo album, 'Romance', and the brunette beauty feels thrilled by the response from her fans.
She told 'Entertainment Tonight': "It feels amazing [to see reactions online].
"I just also have the sweetest, most amazing fans in the world, and just seeing their reactions and seeing how invested they are in the music and seeing what songs they connect to and them just kind of pointing things out in the album just feels so exciting and rewarding.
"I think like, writing the album is amazing, but the second best thing is release day and getting to see what everybody is saying."
Camila and Shawn started dating in July, but the 'Havana' hitmaker recently admitted she first had feelings for Shawn back in 2015, when they collaborated on the hit 'I Know What You Did Last Summer'.
She said: "During 'I Know What You Did Last Summer,' I really bonded with him as more than a friend. I think he did, too, but we were both really young, and he was experiencing the pressures of his career.
"I don't think we knew what to do with those feelings. It was this awkward thing where we both liked each other, but we weren't together. It was just weird."
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