As you may recall, Bristol Palin shocked the world (or the US of A) when it was revealed that she was a pregnant teen during her mother's vice presidency bid. Sarah Palin was (is) against abortion and comprehensive sexual education, so the revelation that her daughter was semi-secretly pregnant swung wide of irony and into karmic kismet territory. Liberal-leaning folks were a little too happy and conservatives were a little too spin-doctor-y.
After Bristol Palin had the child she remained in the public eye as America (or just the media) remained incredibly interested in the life of this conservative powerhouse's teen parent daughter. Then things took a bit of a left turn (pun intended) when young Bristol said in an interview that abstinence-only sex-ed was fairly unrealistic, teens being teens and all.
The breakup comes as a bit of a surprise considering some of the compliments that Bristol has paid Levi Johnston in the press, particularly vis-à-vis his parenting and their future. But per the Radar article, Mercede Johnston (Levi's sister) says that the truth on the ground is not as always as rosy as the media reports it (or as it's spun by whomever is interested in portraying their story in a more favorable light). (Note: We've never heard of such a thing as a media slant or prominent people spinning news to make it look better, but we'll indulge in the fantasy.)
Though we're mildly skeptical about any 'breaking news' regarding the Palin family, we wouldn't be terribly surprised to see a teen relationship end after a pregnancy. Statistically, it's not an easy situation and apparently neither is having a relationship after your parent loses an election. Just ask poor Meghan McCain.