It’s all really so simple, it goes like this, everyone loves love but those who have been cruelly demeaned / hated / abused are angry that someone has hated / abused / demeaned them and no one cared enough to protect them, hence they resent humanity, coupled with jealousy over others who have love, so for example, imagine someone was rich but someone stole that money from him, they would both resent the theft as well as lack of protection (though this is a subconscious resentment) but likewise, then become jealous of those who have money and it isn’t stolen; this would cause them to desire to steal money from those who have it, so “they cannot feel pleasure while I feel pain” (for this is the natural desire of the ego called jealousy.)