If this be error and upon me proved, I never writ, nor no man ever loved. These lines are an example of what

It is a couplet. It is also a figure of speech.

Check this site:

http://grammar.about.com/od/rhetoricstyle/a/20figures.htm

These lines are an example of a Shakespearean sonnet. Specifically, they are the final two lines, or the couplet, of Sonnet 116. The sonnet is a 14-line poem consisting of three quatrains (four-line sections) and a concluding couplet. Each line typically contains ten syllables in a rhythmic pattern called iambic pentameter.

To determine that these lines are from a Shakespearean sonnet, you can follow these steps:

1. Identify the structure: Sonnets have a specific structure consisting of 14 lines in total.
2. Analyze the rhyme scheme: Shakespearean sonnets have a specific rhyme scheme of ABAB CDCD EFEF GG, with each letter representing a different rhyme.
3. Identify the poetic form: The iambic pentameter pattern, where each line has ten syllables with a stressed and unstressed pattern, is commonly seen in Shakespeare's sonnets.
4. Consider the content: Shakespeare's sonnets often explore themes of love, beauty, time, and mortality.

By following these steps and analyzing the lines provided, we can conclude that they are indeed an example of a Shakespearean sonnet.