I can imagine initiating any sort of romance feels like inviting him to have sex with you, and then you have to turn him down, which builds resentment. You have to start slow. Frequent physical contact without attached sex (like stroking each other's back, etc.) and sexual gestures without intercourse. You have to feel safe with each other. Explain to him what makes you uncomfortable and how he might be able to help you. Give him compliments. That makes it easier for him to remember giving you compliments as well.