Starman's Quest

The Lexman Spacedrive gave man the stars - but at a fantastic price. Interstellar exploration, colonisation, and trade became things of reality. The benefits to Earth were enormous but, because of the Fitzgerald Contraction, a man who shipped out to space could never live a normal life on Earth again. Travelling at speeds close to that of light, spacemen lived at an accelerated pace. A nine-year trip to Alpha Centauri and back seemed to take only six weeks to men on a spaceship.
When they returned, their friends and relatives had aged enormously in comparison, old customs had changed, even the language was different. Alan was a spacer, just like his whole family - until, suddenly and without intending to, he in turn jumped ship and remained on Earth. There were times he regretted that. Earth was a bewildering and utterly hostile place. To stay alive, he had to play a ruthless game - and he couldn't even find anyone to tell him the rules.