Meghan Markle helped Prince Harry "open up" about his feelings.
The 32-year-old royal revealed earlier this month that he had almost suffered a breakdown after struggling to cope with the loss of his mother Princess Diana - who tragically died in a car crash in Paris, France, in 1997 when Harry was just 12 years old - and royal sources have now claimed it was Harry's girlfriend Meghan who encouraged him to "talk about his feelings".
An insider told Closer magazine: "Harry fell for Meghan partly because she's so open, and has that American attitude of saying, 'Let's talk about our feelings.'
"He comes from such a stiff-upper-lip culture, but Meghan helped him open up.
"Meghan encouraged Harry to see that, by speaking publicly about his difficult experience, he would really help others, and how being honest might even be a relief.
"No other woman has helped Harry so much emotionally."
The news comes after Prince Harry - who is the younger brother of Prince William - gave a candid interview in which he spoke about "shutting down his emotions" as he grew up determined not to think about the loss of his mother.
He said: "I can safely say that losing my mum at the age of 12, and therefore shutting down all of my emotions for the last 20 years, has had a quite serious effect on not only my personal life but my work as well.
"I have probably been very close to a complete breakdown on numerous occasions when all sorts of grief and sort of lies and misconceptions and everything are coming to you from every angle."
And the royal admitted he has been in therapy "more than a couple of times" in order to help him deal with his grief, and later turned to boxing as a way to vent his frustrations.
He added: "During those years I took up boxing, because everyone was saying boxing is good for you and it's a really good way of letting out aggression. And that really saved me because I was on the verge of punching someone, so being able to punch someone who had pads was certainly easier."
Prince Harry is now campaigning to end the stigma surrounding mental health through his charity Heads Together - which he spearheads alongside William and his wife Catherine, the Duchess of Cambridge - as he hopes to "make a difference to everybody else".
He told The Daily Telegraph newspaper: "Because of the process I have been through over the past two and a half years, I've now been able to take my work seriously, been able to take my private life seriously as well, and been able to put blood, sweat and tears into the things that really make a difference and things that I think will make a difference to everybody else."
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