Spending the night at my boyfriends.

How do I go about asking to let me spend the night with my boyfriend to my dad? I’m 19 one month from turning 20 and my dad isn’t too keen about letting me spend the night with him. I’ve spent the night with him so many times, but my dad doesn’t know about it. I don’t like sneaking around about it either, I wish i was able to be free and open about it to the point where I can go over as frequently as I’d like. My boyfriend is a great guy. If my dad is concerned with me having sex, I’ve already done so in several occasions 😂 my mom is more open and knows all about me, but I live with my dad and he’s so hard to talk to... any advice being in my perspective or the parent? Thanks!