from the "Rehab" Wiki page:

The song was written about Winehouse's refusal to attend an alcohol rehabilitation centre after her management team encouraged her to go. "I asked my dad if he thought I needed to go. He said: 'No but I should give it a try.' So I did, for just 15 minutes. I went in said 'hello' and explained that I drink because I am in love and have %!%@+% up the relationship. Then I walked out."[1] Winehouse later changed her management company.[2]
Oh the interesting parallels!