Here are top eco‑luxury properties in Sri Lanka that are especially well suited for newlyweds — each pairs high-end, romantic amenities with strong nature/sustainability credentials or a low‑impact design. I’ve included why each is romantic for honeymooners, the eco / conservation highlights, the region, and a source so you can read details or book.

1. Jetwing Vil Uyana — Sigiriya (Cultural Triangle)

• Why honeymooners love it: private, ultra‑quiet retreat with thatched pavilions, private balconies and wildlife (wetlands) right outside your room — great for sunrise together and romantic safari/temple day trips.
• Eco highlights: built around a 28‑acre artificial wetland converted from abandoned paddy; designed as an eco‑architecture project with habitat restoration and strong community training programs. (en.wikipedia.org)

2. Heritance Kandalama — Dambulla / Sigiriya

• Why honeymooners love it: dramatic cliff‑and‑jungle setting with sweeping views, candlelit dinners and an iconic infinity pool — intimate and cinematic for newlyweds.
• Eco highlights: Geoffrey Bawa‑inspired integration into the landscape, long reputation for onsite conservation and low‑impact design blending hotel into rock and forest. (Frequently recommended on honeymoon guides and eco‑hotel lists.) (cocolimetravels.com)

3. Cape Weligama (Resplendent Ceylon) — Weligama / South Coast

• Why honeymooners love it: cliff‑top suites and private villas with infinity pools, sunset views and private‑dining options — very luxurious and secluded.
• Eco highlights: resort operates with a focus on local sourcing, marine activities (whale/dolphin watching responsibly) and island/coastal conservation partnerships; offers curated nature experiences. (resplendentceylon.com)

4. Santani Wellness Resort & Spa — Kandy Hills / Central Highlands

• Why honeymooners love it: ultra‑private wellness retreat with villa‑style rooms, tailored spa/wellness programs, candlelit private dinners and mountain views — ideal for couples wanting rejuvenation and privacy.
• Eco highlights: low‑density design, emphasis on local food, wellness built around natural setting and sustainably‑sourced materials; highly rated for architecture that respects the landscape. (srilanka-bespoke.com)

5. Wild Coast Tented Lodge (or similar tented lodges near Yala) — Yala National Park area

• Why honeymooners love it: luxury safari tents for adventurous couples who want romance plus wildlife (leopards, birds), private dining and bush‑style luxe comfort.
• Eco highlights: camp designs minimize footprint, support local conservation and often run community and park‑support programs; ideal for wildlife‑focused honeymoons. (remotelands.com)

6. Anantara Peace Haven Tangalle Resort — Tangalle / South Coast

• Why honeymooners love it: secluded beach cove, ocean‑view villas and intimate private‑dining/spa options for couples.
• Eco highlights: coastal and marine conservation activities, beach protection programs and local community engagement; resort emphasizes sustainable practices and local sourcing. (en.wikipedia.org)

7. The Six (The Six Weligama) — Weligama (south coast)

• Why honeymooners love it: private‑villa style accommodation with ocean views, private pools and surfing/boat trips — great for couples who want a stylish, contemporary beach hideaway.
• Eco highlights: small villa footprint, use of local materials and local‑led experiences; many honeymoon packages include eco‑friendly experiences. (cocolimetravels.com)

8. Small boutique eco‑lodges near Galle / Kahanda Kanda area

• Why honeymooners love it: hilltop villas among tea and jungle with private pools, huge privacy and romantic architecture — intimate, very “away from it all.”
• Eco highlights: many boutique properties in the Galle hills focus on local sourcing, low‑impact construction and nature conservation; ideal for couples wanting culture, tea‑estate walks and privacy. (Kahanda Kanda and similar are frequently recommended on honeymoon lists.) (cocolimetravels.com)

Quick planning tips for newlyweds

• Combine coastal and hill experiences: a common honeymoon route is 3–4 nights in the south coast (Weligama/Cape Weligama or The Six) + 2–3 nights in the Cultural Triangle or central highlands (Jetwing Vil Uyana or Santani) for variety (beaches, wildlife, culture, wellness).
• Best seasons: South coast/Weligama/Tangalle — November to April is generally best for calm seas; east coast (Arugam Bay) is best April–September; central hills are pleasant year‑round but can be cooler and wetter in monsoon months. Check exact travel windows when you book. (Seasonality can change year to year — confirm with hotels/flight providers.)
• Ask hotels for honeymoon inclusions: many properties offer complimentary extras (romantic dinners, couples’ spa treatments, upgrades) — mention “honeymoon” when booking.
• Responsible bookings: confirm the property’s current sustainability practices (waste reduction, reef/park support, community programs) and ask how your stay supports local conservation.

If you want, I can:

• Narrow this to “top 4” based on exactly the kind of honeymoon you want (beach, wildlife/safari, wellness/retreat, culture + luxury).
• Check current availability, typical nightly rates for your travel dates, or pull direct booking links for any of the properties above.