Step 1: Analyze the cartoon.
The human perceives the dog’s behavior as finding happiness in simplicity. Conversely, the dog's internal monologue indicates it feels burdened by emotional obligations.
Step 2: Match with options.
- Option A: Addresses love and sacrifice, deviating from the cartoon's core theme. - Option B: Concerns identity influenced by external views, which is unrelated to the cartoon. - Option C: Proposes that reality is random, which is too general. - Option D: Discusses the weight of obligation eclipsing personal identity; partially applicable but not exact. - Option E: Accurately reflects the cartoon's point that our understanding of others' circumstances can be fundamentally mistaken.
Step 3: Conclude.
Therefore, Option E offers the most accurate explanation.
Final Answer: \[\boxed{\text{E}}\]