Love is a powerful emotion, making the weak strong. Tsuzuki realized years ago that his strength was in his love for others. But there are many kinds of love, and few last forever.
Tsuzuki's been around a long time, too long to be surprised at abandonment. But not long enough to stop loving.
So Tsuzuki loves with quickly fleeting fancies, never dwelling on anything, least of all the important things. Least of all Hisoka. Because emotions frighten Hisoka most of all, and if he ever realized how much he meant to Tsuzuki, he'd run away and never look back.
Right?