David Heiss, 21, stabbed Matthew Pyke 86 times in a brutal attack after his girlfriend Joanna Witton, whom the German had met through a computer games website, indicated she was not interested in his advances.
Heiss forced his way into the flat Pyke shared with Witton in Nottingham, central England, and repeatedly stabbed him last September, the crown court in the city heard.
As he was dying, Pyke, 20, used his own blood to write the first three letters of Heiss's name on the side of his computer to alert police to his killer's identity.
Heiss, from Limburg, near Frankfurt, had met Witton online, on the warscentral.com site she ran with Pyke.
The court heard that Heiss managed to obtain the address of her flat from a fellow game player and twice travelled to Britain, in June and July last year, to meet Witton face-to-face.
She and Pyke, her long-term boyfriend, allowed him to sleep in their flat before he returned to Germany, but Heiss became more persistent and the Britons became increasingly concerned by his behaviour.
In an online message, Pyke told the German: "I hate you because you decided to come into our lives. I hate you for ever laying eyes on the girl I have dedicated my life to. I hate you for your desperation."