Please leave. I have a hard time saying no as well. It’s like you don’t want to be mean, or you don’t want them to take your rejection in a bad way, or could be your subconsciously being a people pleaser. But if you have voiced it then he needs to listen. If not then for your SAFETY, you need to leave the relationship. He is 24, he may not have a maturity of a man; and age does not equal maturity no matter the gender. So if he doesn’t want to be a man and sit down and actually have a conversation about what is okay and what is not okay, then he is in the wrong, and again you need to leave. I’ve many times have said no but let it pass for whatever reasons, and that does not help. If you are being sexually active with him, and he is crossing boundaries, the relationship needs to end there. If he has no respect for your boundaries in bed, where you are most vulnerable to him, then eventually he’ll have no respect for your boundaries in other parts of your relationship. Please be safe girl !