Courteney Cox ended her 17-month engagement to Johnny McDaid — and trust issues were partly to blame, sources tell In Touch.

“She didn’t want to let him go but had no choice because she started to suspect he was losing interest in her,” an insider claims. “Right before Jen Aniston’s wedding, she felt something wasn’t right. Johnny was acting distant and spending a lot of time in England.”

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courteney cox johnny mcdaid

Courteney Cox and Johnny McDaid.

The source adds that Courteney even hired a private investigator and “ended things soon after.”

But then Courteney caved and took the Snow Patrol rocker back.

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“She was deeply in love and thought she could fix him,” says the insider.

courteney cox johnny mcdaid

Courteney Cox and Johnny McDaid.

No luck, even with counseling: “They loved each other dearly, but had major trust issues,” another source agrees.

For more on this and all your favorite celebrity couples, pick up the latest issue of In Touch, on newsstands now!