Jennifer Aniston, happy birthday!

The blonde bombshell celebrates her 53rd birthday today, but it will be a melancholy day for her.

She is well aware that she is one of Hollywood's most accomplished and affluent actresses. But, like the rest of us, the "Friends" actress can't disguise her sadness about growing older.

A source told OK magazine that she's feeling down while filming the smash Netflix sequel "Murder Mystery 2."

"She seemed to be sad about something and was far from her usual bubbly self."

The insider went on to say, "It was like she had the weight of the world on her shoulders."

Jennifer Aniston is said to be having a nasty case of the birthday blues. The insider also revealed that, despite the fact that she is in Hawaii, this year's voyage around the sun is her "loneliest" ever.

This is due to the fact that she has yet to meet her true love.

"She'll put on a brave front and pretend she's happy with being single," the source continued.

"But the reality is, she's finding it difficult to share her life with someone important."

After her divorce with Justin Theroux, the "Breakup" actor admitted last year that she was ready to share her life with someone already.

"No one of consequence has yet crossed my radar," Jennifer, who was married to Brad Pitt at the time, said.

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However, one insider claims that this is due to her preference for guys.

What makes matters worse is that the A-lister has apparently turned into a recluse, preferring to stay at home and feel sorry for herself rather than go out with her pals.

To keep herself occupied, she even puts herself into initiatives and new business enterprises, according to an insider.

"She'll check in with friends over the phone. But most of the time, it's work and more work."

While Jennifer Aniston has maintained friendships with her ex-husbands, she is unlikely to have a huge birthday bash for herself this year since she apparently does not feel like it.

Though her job is doing well, she claims that her hectic work schedule isn't filling the emptiness in her life, and she is worried that she may never find love again.

Jennifer is also concerned about the fact that her time is running out.

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