Britney Spears' younger sister Jamie Lynn has called off her engagement to boyfriend Casey Aldridge after deciding she is too young to marry.

The 18-year-old actress accepted Aldridge's proposal early last year when she was pregnant with their daughter, Maddie Briann.

However, according to In Touch Weekly magazine, the Zoey 101 star has changed her mind about marrying her teenage sweetheart and is happy just being boyfriend and girlfriend. The younger Spears has even returned her diamond engagement ring to Aldridge.

A close pal tells the publication, "Casey proposed when Jamie turned 17. He gave her a gold band with numerous diamonds and one larger stone, but now she has given it back to him."

"Jamie wasn't ready to get married. It's been more than enough for her to adjust to new motherhood for now."

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(This news article provided by World Entertainment News Network)