I’m going to sound so lame

Okay so... I used to be able to ride my fiancé all the time and do a million different positions. Still can, but lately whenever I want to get on top of him I can’t seem to get his dick to go in. He’s rock hard and I’m soaking wet. Idk what I’m doing wrong but I LOOOVE being on top of him and I can’t seem to find my opening. 🤦‍♀️ Advice?! Help?!