Adam Johnson will need treatment for his "compulsive drive to have new sexual experiences", a judge has said.
But despite the court being told Johnson searched the internet for a website called "Nice Young Teens", experts said there was no evidence the player had an interest in pre-pubescent children.
A prosecutor said there was no evidence there was anything illegal on the teens site.
Judge Jonathan Rose told the player the offences against the teenager in the case happened "at a time when you were engaged in frequent sexual intercourse with multiple partners".
According to the judge, Johnson told a psychiatrist: "I treated (the teenager) like any of the girls I met.
"I put her age out of my mind. I was sexually interested but she was just another girl, another opportunity. She was attractive enough. Another one to get with."
The judge said to him: "When you had moved to play for Manchester City you embarked on an extensive social life which involved sexual activity on a very frequent basis with a number of different partners, even when you were ostensibly in a settled relationship.
"You do not suffer from any mental illness but are described as having a very high libido and a tendency to engage in sexual activity to a compulsive degree."
During Johnson's sentencing hearing, Kate Blackwell QC, prosecuting, told the judge that the player had a history of meeting girls for sex as he returned from training, describing it as a "clandestine habit".
Miss Blackwell said a medical report concluded Johnson "believes he has a right to sex".
Dr Philip Hopley, a consultant psychiatrist giving evidence for the defence, told the court: "This is a man who, at the age of 28, is socially and psychologically immature."
Dr Hopley said Johnson developed very late physically and had low self confidence as a youngster.
He said he believed that as a professional footballer Johnson developed his confidence and self-esteem very quickly and this, combined with the availability of willing women, led to his "compulsive sexual behaviour".
The doctor said he found no evidence in Johnson of an attraction to pre-pubescent children or "sexual perversion".
Orlando Pownall, defending, told the judge: "He does not pose a significant risk of harm to children, for (victim) was not selected on her age but despite her age."
He said that despite the huge publicity surrounding the case, no other underage girls have complained about Johnson.
"This is not the case of a predatory paedophile who has sought out children for sexual purposes," he said.
At a previous hearing, a judge was told about a social media discussion between Johnson and a female called "Rosie" involving the two of them planning to meet up in "Darlo" to find a place for them to have sex.
There was a suggestion from Johnson that they may find somewhere like his car bonnet to have sexual relations.
Miss Blackwell said this and other messages "demonstrate the defendant, rather than think first of his family, career and his partner, he is in fact somebody in the habit who at the same time as he engages with the complainant is planning sexual activity in or on his vehicle with others not connected to his family".