The speaker describes one good day with someone who matters a great deal to them. Nothing dramatic happens. They talk, they dance, the other person holds their hand, and they laugh together. The speaker hands over a card and says thank you for putting up with them for two years, which suggests a long relationship, though the poem doesn't say what kind.
What stands out is how the happiness is handled. The speaker keeps listing small kindnesses: "you didnt protest," "you didnt leave me," "you were nice." These read as if the speaker is surprised by them and doesn't quite expect to be treated gently. The repeated "But today was a good day" sounds like someone reassuring themselves, and the admission "I may have been scared" hints at nerves underneath the joy.
The mood is tender, hesitant, and a little fragile. The plain, simple wording makes the happiness feel honest, as if the speaker is holding onto the day before it slips away.