Taylor Swift and Calvin Harris were spotted having dinner at Giorgio Baldi restaurant in Santa Monica, California, on Tuesday evening.
"They were very close together, leaning in to speak to each other and laughing a lot," an onlooker tells PEOPLE.
Swift, who kicked off her 1989 world tour last week in Tokyo, wore an all-black ensemble with matching clutch, complemented by – you guessed it – that bold red lip.
"Taylor looked gorgeous. It was a very sexy but classy look," said the witness. "She was glowing, she seemed incredibly happy but also very at ease with Calvin."
The "Style" singer is back stateside ahead of a performance at "Rock in Rio USA" in Las Vegas on Friday – and appeared to be making the most of her time off.
"They were dressed up and enjoying themselves, talking and laughing the entire time," said the source.
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Rumors about the two began swirling in March, when they were spotted getting close at a Kenny Chesney concert. Most recently, Swift, 25, and Harris, 31, got cozy at 102.7 KIIS FM's Wango Tango on Saturday.
Although neither has explicitly confirmed their romance, Harris posted an Instagram photo of Swift's two beloved cats in April, which all but seals the deal: Being introduced to Meredith and Olivia is undoubtedly a huge step in anybody's relationship with Taylor.