Kristen Stewart
Kristen Stewart is sad over reports that Robert Pattinson and FKA twigs are engaged Jason Merritt/Getty Images

American actress Kristen Stewart is reportedly sad over reports that former boyfriend Robert Pattinson and FKA twigs are engaged.

It was previously reported that the Remember Me actor and the 26-year-old singer, whose real name is Tahliah Debrett Barnett got engaged last week.

According to Life & Style, the 24-year-old Camp X-Ray star is shocked that the couple got engaged after dating just for five months.

"She was hurt at first, but now she's just worried that Rob and FKA are moving too fast," a source said, according to Hollywood Life.

It was previously reported that Pattinson is planning to invite Stewart, to his wedding with twigs.

In 2012, Pattinson ended his relationship with Stewart, his Twilight co-star and girlfriend of four years, after it was confirmed that she cheated on him with British director Rupert Sanders.

The 24-year-old Camp X-Ray star and Sanders, who worked together on Snow White And The Huntsman, were photographed kissing in Hollywood Hills.

Earlier it was reported that Stewart felt twigs was using Pattinson for fame.

Pattinson and twigs are very open about their relationship. At the Mercury Music Prize Awards, twigs was asked how her relationship with Pattinson was going, to which she replied: "Very good, thanks."

During an interview with The Guardian's magazine, The Observer, she went even further and called Pattinson "The man that I love."