Justin & Jessica's Miami Heat

Justin Timberlake will sing the praises of his lady-love Jessica Biel on his next CD.

"He's been writing autobiographical songs. A lot of them reflect his relationship, being in love and starting a family," a pal tells OK!.

The couple recently had a romantic rendezvous in Miami, sharing a lunch of egg salad and turkey club sandwiches at Table 8 restaurant on May 28. Prior to that, they spent the Memorial Day weekend sailing on a private boat and having a tandem workout session at David Barton Gym, where JT,27, told employees that Jess,26, was his sister!

Riiiight!