The 24-year-old, who signed for United in a £4million deal, believes that without his brother and girlfriend, he wouldn't have stayed at Old Trafford.
Buttner found chances hard to come by this season after being brought in as back up for Patrice Evra, and featured in only 13 games in all competitions for United.
"I now know about homesickness. I'd think about my family and friends at home many times," he told The Sun.
"How they were, what they were doing, little things like that."
The full-back revealed, though, that it was the family who followed him to England that persuaded him to persevere and he is looking ahead to another season at Old Trafford.
"I did not give up and I have my girlfriend Laura and brother Denny to thank for that," he added.
"They were always there for me in England. I could call on them any time. I needed their warmth.
"I'm a fighter. But had I been on my own, I'd have got on a plane back to Holland a long time ago."