Hi Priya,
In Poovar, there is poovarislandresort, beautiful and private. Chk out website-www.poovarislandresort.com
In Munnar, there is club mahindra, cloud9, tall trees.
I had visited cloud9 and believe me it was the best romatic place i have been. Mist, clouds, silence, greenery ooff, amazing is the only word.
In Kumarakom, there is coconut lagoon. believe me , its slightly expensive but the best. I have been there too

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Hope this information helps.
Sheeba