Question: who is the song perfect by ed sheeran about
[{'answer': 'his girlfriend Cherry Seaborn', 'provenance': [{'wikipedia_id': '52836376', 'title': 'Perfect (Ed Sheeran song)', 'start_paragraph_id': 4, 'start_character': 120, 'end_paragraph_id': 4, 'end_character': 149, 'bleu_score': 1.0, 'section': 'Section::::Composition and production.\n'}]}]