Absolutely, I'd love to help you plan your trip to Vietnam for 3 days as a couple! Vietnam is a beautiful country with so much to offer, from bustling cities to serene landscapes and delicious cuisine. Here's a suggested itinerary for your trip:

Day 1: Hanoi

• Start your day with a visit to Hoan Kiem Lake in the heart of Hanoi. Enjoy a leisurely stroll around the lake and visit Ngoc Son Temple.
• Explore the Old Quarter, known for its narrow streets, ancient architecture, and vibrant markets. Don't miss trying some local street food like pho or banh mi.
• Visit the Temple of Literature, Vietnam's first national university, and soak in the history and culture of the country.
• In the evening, head to the Hanoi Night Market for some shopping and delicious street food.

Day 2: Halong Bay

• Take a day trip to Halong Bay, a UNESCO World Heritage Site known for its stunning limestone karsts and emerald waters. You can book a cruise or a boat tour to explore the bay.
• Enjoy activities like kayaking, swimming, and visiting caves. Don't forget to capture the breathtaking views of the bay.
• Spend the night on a cruise ship or return to Hanoi, depending on your preference.

Day 3: Hoi An

• Fly to Hoi An, a charming ancient town known for its well-preserved architecture, lantern-lit streets, and vibrant markets.
• Explore the Old Town on foot or by bicycle, visiting historic sites like the Japanese Covered Bridge and the Assembly Hall of the Fujian Chinese.
• Take a cooking class together to learn how to make traditional Vietnamese dishes.
• In the evening, stroll along the Thu Bon River and enjoy the magical atmosphere created by the lanterns.

This itinerary offers a mix of cultural experiences, natural beauty, and culinary delights, perfect for a couple looking to explore the best of Vietnam in 3 days. Let me know if you need any more details or if you'd like to customize your trip further!