"Shame"

The guy in this song wants another chance with his girl because he knows that he is wrong and he admits it here. The tone here would be regretful. That means that someone feels bad about what they've done in the past. using "guilt" and "blame" it gives the connotation of bad or sad and even pulls at the idea of regretful. Regretful can be also with feeling remorse for what they've done. "boatloads of shame" shows that they are ashamed of what they've wrongly done and are regretful, just like the tone suggests.