seems that there's a number of you who do not know why the answer is friendship.. Here is it.
From the first line, it is easily mistaken as love. But it is saying thet without any promises. True friendship do not need any promises, just a word of trust. Secondly, there is not a need to buy things like chocolate just like for lover but just a simple greetings will be enough. Lastly, a friend would be able to warm your heart, even without the glaring sunlight, by just simply give a word of comfort or encouragement. That's all about it. Hope that you will understand.