She didn't want to admit to Antonin what was really going on in her mind. When she told him her suspicions about what Rodolphus had planned for her, he didn't even know how to respond. The explanation she gave about the horrible man spending years trying to turn her more into his wife with changes inside her mind angered him, but he'd somehow managed to keep a handle on his temper. Likely he was biding his time until he could rid the world of the entire Lestrange family. She felt the same. Only the fear that whatever the spell he had left in her mind activating when he was killed prevented them from going straight to that option. Once Mr. Akingbade was able to get the necessary information about what the spell was and how it could be removed then Rodolphus" murder would be possible.