The couple began dating in February (12) and the Grammy-winning Dj even featured Goulding's vocals on his EP Bangarang.
However, the music stars have since parted ways after struggling to sustain a long-distance relationship.
A source tells Britain's The Sun, "It's really sad, they were really good for each other. They just couldn't make it work. They both have successful careers and live in different countries."
Earlier this month (Oct12), Goulding admitted she would love to collaborate on an entire album with Skillex, insisting, "In an ideal world we'd love to make a whole record together... but it just so happens that we're both ridiculously busy... I have fun listening to his new stuff because it blows my mind and it's so clever to me, so fascinating it makes me want to laugh, and I laugh because it's so brilliant."