The love of a brother. The love of a father. The love of God. Each one of these loves is addressed in "This Hour and What Is Dead." In fact, the word "love" itself pops up four times in this short poem. Love connects our speaker to the loved ones he has lost, but it is also a burden to him, because their memory is ever present. And God's love? Well, that's a whole different story.
In this poem, love is a burden, not a gift. While loving a dead brother may sound nice, for our speaker it's nothing more than a curse.
God's love is the real problem here, because God's love leads to the speaker's insomnia. The more God loves him, the harder it is for him to understand why God would allow his loved ones to die.