Can homosexuals express true love for each other?

It is not impossible for homosexuals to express true love for each other. What is impossible is for their sexual relations to be a sign of that true love in the way that marital relations between a man and a woman is a sign of marital love.

True love can encompass affection and romantic attraction, but they do not constitute true love and true love is not dependent upon them. It must also be said that affection and romantic attraction are not, in and of themselves, a substitute for true love. Love is an action of the will that is willing to sacrifice oneself for the sake of the ultimate happiness of the beloved. To be willing to sacrifice oneself includes sacrifice of one's own desires and interests, especially when those desires and interests would prevent the beloved from attaining ultimate happiness. Ultimate happiness, the ultimate good in life for which we strive, is union with God.

If you can accept this definition of love as "true love," then it should be readily seen why it is not impossible for homosexuals to express true love but not through their sexual relations. They can express true love for fellow homosexuals by refusing to do anything that would prevent their beloved from union with God. As homosexual sexual relations are gravely contrary to natural law and intrinsically disordered, engaging in such relations is indeed an impediment to be renounced for the sake of true love. That is why the Catholic Church calls upon homosexuals to embrace a life of chastity. The Church is not merely denying homosexuals a chance for sex; it is pleading with homosexuals to fully embrace love and to be embraced by God, who is Love.