To begin with, the phrase "unconditional love" is an extremely strong claim. It means something that does not depend on any condition, reason, or circumstance. If that's true, then why do you love that person in the first place?
Any answer you give is already a condition. "I love them because they're kind." "Because they supported me." "Because they're my sibling." "Because they understand me." Every "because" is a condition.
Second, you don't just wake up one day and randomly decide to love someone. Love is a response to qualities, experiences, or a connection with another person. If love is a response, then it has causes. And if it has causes, then it depends on conditions. #conversation source