Joe Alwyn feels "slighted and distraught" after his ex-girlfriend Taylor Swift reportedly moved on to a budding romance with Matty Healy after their split.
Rumours of Taylor and Matty's relationship started to swirl earlier this month, just weeks after news broke of her split from Joe after six years together.
A source has claimed Joe is "doing his best to keep busy", but has been left unhappy with his former girlfriend's new romance.
"Joe feels slighted and is distraught after seeing her budding relationship with Matt, but is doing his best to keep busy and focus on himself.
"Joe was aware that Taylor and Matt were making music together and collaborating. She told him that they had become friends and he trusted her," they said.
Speaking to the Daily Mail, the source denied there had been an "overlap" between Taylor's two romances.
Since news of their alleged romance broke, Matty and Taylor have been spotted out and about on a number of occasions.
The pair were all smiles as they were seen leaving the Electric Lady recording studio in New York earlier this week.
Taylor beamed as she left the building, while The 1975 frontman followed close behind.
The Shake It Off hitmaker, 33, opted for a casual outfit and wore a black miniskirt paired with a purple and grey NYU jumper.
Matty wore an all-black ensemble which consisted of a baggy jumper and comfy trousers.
They were also spotted enjoying a romantic date night at Casa Cipriani last week.
Matty and Taylor were seen "kissing and cuddling" by fans, who captured pictures of the date and shared them on social media.
An onlooker said the pair were seated next to each other and were looking very cosy as they waited for their food while security was around them.
Musician Matty was also seen dancing and bonding with Taylor's dad, Scott Swift, at one of her Philadelphia performances.
Taking to Twitter after the concert, fans started speculating that Matty is now "part of the family".
"MATTY UPGRADED FROM THE TENT TO A LOUNGE AND IS STANDING NEXT TO TAYLOR’S DAD??," penned one fan alongside a snap of Matty standing next to Scott.
"HE REALLY IS PART OF THE FAMILY NOW WHAT?!?" another tweeted.
"Why did we move on from the fact that he’s literally walking around with Taylor’s dad again huh I guess they bonded last night," someone else said.
* Follow Mirror Celebs on Snapchat, Instagram, Twitter and Facebook.