Great—here’s a romantic, couple-focused beach-resort itinerary for Sri Lanka with options for different tastes (luxury, secluded, active). I’ve included daily plans, recommended resorts for each stop, travel notes and seasonality so you can pick dates that give the best beach weather.

Quick season note (important for planning)

• South & west coast (Negombo, Bentota, Galle, Mirissa, Tangalle, Unawatuna): best November–April.
• East coast (Trincomalee, Arugam Bay, Pasikuda): best May–October.
  (Plan south/west coast trips in Nov–Apr; east coast in May–Oct). (thetimes.co.uk)

Sample 10–12 day romantic beach-resort itinerary (south & west coast — ideal Nov–Apr) Day 1 — Arrival / Negombo

• Land Colombo (CMB), transfer ~30–45 min to Negombo to recover from jet lag.
• Stay: Sentido Heritance Negombo or a boutique beachfront hotel with a spa. Evening beach walk & seafood dinner. (thetimes.co.uk)

Day 2–3 — Galle & Koggala / boutique villa

• Drive (~2–2.5 hrs) to Galle. Spend an afternoon exploring Galle Fort (colonial streets, cafes, sunset at the ramparts).
• Stay near Koggala or Galle for privacy and beach access. Recommended: Kahanda Kanda (for a lush lowland/romantic villa feel) or a small boutique villa with private plunge pool. (thetimes.co.uk)
• Day 3: optional Koggala Lake boat trip, stilt-fishing viewpoint, in‑villa candlelit dinner.

Day 4–5 — Mirissa (whale watching + beach time)

• Short coastal drive to Mirissa (~30–45 min). Book an early-morning whale/dolphin excursion (seasonal peak Dec–Mar). Relax afternoons on Mirissa’s crescent beach; sunset at Coconut Tree Hill or Parrot Rock. Good for couples who want a mix of activity and chill time. (honeymoonguidesrilanka.com)
• Stay: boutique beachfront villas or luxury options near Mirissa.

Day 6–7 — Tangalle / Amanwella or Hiriketiya

• Head east along the coast to Tangalle (~1–1.5 hrs). Choose Tangalle for wide, quiet beaches, or Hiriketiya Bay for a more bohemian surf-yoga vibe (great for active couples).
• Luxury pick: Amanwella (private suites, plunge pools, secluded beach) — excellent for romantic privacy. (TravelTriangle.com)
• Activities: private beach dinner, local village visit, spa treatment, short snorkeling trips.

Day 8–9 — Bentota / Galle coast (watersports & relaxation)

• Drive west toward Bentota (~2.5–3 hrs). Bentota is great for water sports, long beach walks and Ayurvedic spa treatments. Consider a night with beachfront dining, river boat ride on Bentota Ganga. Recommended: Taj Bentota / Saman Villas / boutique resort with beach access. (indianholiday.com)
• Activities: windsurfing/kayak, Ayurvedic couple’s massage, sunset cruise.

Day 10 — Optional Colombo quick stop or airport transfer

• If you fly out from Colombo the next day, either transfer straight to Colombo (allow 1.5–2.5 hrs depending on traffic) and stay close to the airport, or add an overnight in Colombo to explore the city and restaurants.

Alternative 10–12 day itinerary if you prefer east-coast (May–Oct)

• Negombo → Sigiriya / Cultural Triangle (brief stop) → Trincomalee or Pasikuda (beaches) → Arugam Bay (surf & chill) → back to Colombo. East coast is quieter and better in May–Oct. (thetimes.co.uk)

Top resort suggestions by mood (examples to research & book)

• Ultra-luxury seclusion / plunge pools: Amanwella (Tangalle), Cape Weligama (cliff-top suites near Mirissa). (TravelTriangle.com)
• Romantic, beachfront colonial/heritage: Saman Villas (Bentota area). (bluelankatours.com)
• Boutique, design-forward: Kahanda Kanda (near Galle; intimate suites & villas). (thetimes.co.uk)
• Surf-yoga / relaxed-cafe vibe: Hiriketiya area (near Tangalle) for couples who want surfing + chill beach cafés. (honeymoonguidesrilanka.com)

Logistics & practical tips

• Transfers: Private car with driver is common, comfortable and economical for couples—allows scenic stops. Domestic flights available between Colombo and some southern hubs (seasonal).
• Pace: 2–3 nights per beach stop is ideal for couples—enough time to relax without constant packing.
• Book ahead: Popular honeymoon/romantic suites fill early in high season (Nov–Apr). Reserve special dining, spa treatments and excursions in advance.
• Health & safety: Swim at lifeguarded beaches where possible and check local conditions; turtle nesting season (Dec–Jan in some spots) is a special experience—follow conservation rules. (indianholiday.com)

If you want, I can:

• Build a day-by-day itinerary for exact dates you have in mind (including travel times and drive maps), or
• Compare 3–4 specific resorts for a chosen stop (prices, room types, pros/cons) and recommend the best for couples and for your budget.

Which do you prefer: a ready-to-book 10-day plan for Nov–Apr (south/west coast), or a tailored itinerary for specific travel dates and budget?