According to vocabulary.com, blissfulness is a state of being very happy. It is the noun form of the adjective blissful. Blissful means to be full of bliss or supreme happiness.
- Anastasia reveled in her blissfulness.
- The music complemented the blissfulness of the crowd.
- She enjoyed the blissfulness of being in the hot tub.
- Blissfulness filled the town over the news of John coming home from deployment.
Some synonyms include heaven, over the moon, paradise, and walking on air.