Final answer:
The love Tucker holds for Greg, which is characterized by happiness and no expectations, is known as unconditional love. It is a selfless affection given without any conditions, based on acceptance and care for the well-being of the other person.
Step-by-step explanation:
The type of love described, where Tucker loves Greg, finds happiness in his presence, and expects nothing in return, is often referred to as unconditional love.
Unconditional love is characterized by complete acceptance and affection without any expectations or conditions placed upon the relationship. It is a selfless form of love that does not depend on any action or circumstance and is given freely.
In psychological terms, this may also relate to the concept of altruistic love where a person is concerned for the well-being of another without any desire for personal gain.