Spreading legs stings?

I love my man for the way he is. His personality, mindset, body, all of it. I have a sticky situation for myself. My boyfriend likes it if I sit on his lap, facing him, each leg next to the sides of his hips. But it’s kind of hard if I’m not flexible and my legs don’t spread apart far enough. So between my legs were my thigh meets my hips sting. What tips could I do to make my body not hurt and more easier to do this?😅 Like what kind of stretches could I do?