Lord of the Forest by Elizabeth Keysian

She failed to save the man she loved. She won’t make the same mistake again.
Desperate to avoid a suffocating marriage, Clemence plans to dazzle at court, and remain as chaste as The Virgin Queen. Then she’s rescued from kidnappers by the mysterious Lancelot, and only a betrothal to him can save her reputation. But what could induce her father to give her to a man with no memory, no status, and no home but the forest? Especially when that man has a propensity for throwing people into horse troughs, getting himself poisoned, and being accused of murder.

In his forest home, he’s a king among both beasts and men.
Lancelot does everything differently. He can’t help it; he’s been living free in the forest with no memory of shame, sin or the reason for wearing clothes. No memory of anything at all, in fact, although his dreams reveal he’s had a close brush with death. But was he a victim or quite the opposite?

Living hand-to-mouth in his woodland lair, Lancelot is used to helping himself to what he wants, and he wants Clemence. But when she drags him back into the real world, he soon realizes that she will either bring him salvation or oblivion.