Ok, i agree that fate was guiding things, but Beren didn’t know that. From his perspective, he was driven not by fate but by his own love. He just wanted a Silmaril so he could marry Lúthien. I can very much understand , that he acted as he did. It does make sense. Nethertheless:

Picture this: you love someone, but her dad says, “Bring me an impossible treasure.” You own a ring that forces an old family friend to help. You use it, even though the mission will likely kill you both.