The Grammy-winning singer, 26, celebrated her ex-husband's 28th birthday this weekend with a visit to the Jazz After Dark bar in London. The club's owner, Sam Shaker, tells PEOPLE that the couple are still enamored with one another.
"They are in love with each other," Shaker says. "If people would not interfere with all their life, they are amazing together … They are happy together, and that's all that matters to me."
Winehouse and Fielder-Civil were married in May 2007 in Miami. They were divorced last July after Fielder-Civil said Winehouse's alleged adultery was "intolerable."
Fielder-Civil spent almost a year of their marriage behind bars after pleading guilty to charges of assault and attempting to pervert the course of justice.
Winehouse's rep had no comment.
With reporting by SIMON PERRY