I have found in the Free Dictionary 1 these definitions:
Too complicated to be understood by one or someone else.
Bypassing one's or someone else's authority.
Lingering in one's mind as a source of concern or worry.
But it (seems to me) doesn't fit with the rest of the phrase below:
He said he loved me but this was over his head.
So: 1 Could you please tell me what the meaning of " be over one's head" here is?
2 What does "this" refer to?
The fuller text is: (It was extended after some comments made it essential!)
When I arrived at the peak, Mother was making the Thanksgiving meal. The large oak table was covered with jars of tincture and vials of essential oil, which I cleared away. Charles was coming for dinner. Shawn was in a mood. He sat on a bench at the table, watching me gather the bottles and hide them. I’d washed Mother’s china, which had never been used, and I began laying it out, eyeing the distance between each plate and knife.
Shawn resented my making a fuss. “It’s just Charles,” he said. “His standards aren’t that high. He’s with you, after all.”
I fetched glasses. When I put one in front of him, Shawn jabbed a finger into my ribs, digging hard. “Don’t touch me!” I shrieked. Then the room turned upside down. My feet were knocked out from under me and I was swept into the living room, just out of Mother’s sight.Shawn turned me onto my back and sat on my stomach, pinning my arms at my sides with his knees. The shock of his weight forced the breath from my chest. He pressed his forearm into my windpipe. I sputtered, trying to gulp enough air to shout, but the airway was blocked.
[...] Charles arrived early—Dad hadn’t even come in from the junkyard yet— and sat at the table across from Shawn, who glared at him, never blinking.
[...] I passed Shawn carrying a large china plate of dinner rolls, and he stabbed my gut so hard it knocked the wind out of me. I dropped the plate. It shattered.
“Why did you do that?” I shouted.
It happened so quickly, I don’t know how he got me to the floor, but again I was on my back and he was on top of me. He demanded that I apologize for breaking the plate. I whispered the apology, quietly, so Charles wouldn’t hear, but this enraged Shawn. He grabbed a fistful of my hair, again near the scalp, for leverage, and yanked me upright, then dragged me toward the bathroom. The movement was so abrupt, Charles had no time to react. The last thing I saw as my head hurled down the hall was Charles leaping to his feet, eyes wide, face pale.
[...] The next thing I remember, Charles was lifting me and I was laughing—a shrill, demented howl. I thought if I could just laugh loudly enough, the situation might still be saved, that Charles might yet be convinced it was all a joke. Tears streamed from my eyes—my big toe was broken—but I kept cackling. Shawn stood in the doorway looking awkward.
“Are you okay?” Charles kept saying.
“Of course I am! Shawn is so, so, so—funny.” My voice strangled on the last word as I put weight on my foot and a wave of pain swept through me. Charles tried to carry me but I pushed him off and walked on the break, grinding my teeth to stop myself from crying out, while I slapped playfully at my brother.Charles didn’t stay for supper. He fled to his jeep and I didn’t hear from him for several hours, then he called and asked me to meet him at the church. He wouldn’t come to Buck’s Peak. We sat in his jeep in the dark, empty parking lot. He was crying.
“You didn’t see what you thought you saw,” I said.
If someone had asked me, I’d have said Charles was the most important thing in the world to me. But he wasn’t. And I would prove it to him. What was important to me wasn’t love or friendship, but my ability to lie convincingly to myself: to believe I was strong. I could never forgive Charles for knowing I wasn’t.
I became erratic, demanding, hostile. I devised a bizarre and everevolving rubric by which I measured his love for me, and when he failed to meet it, I became paranoid. I surrendered to rages, venting all my savage anger, every fearful resentment I’d ever felt toward Dad or Shawn, at him, this bewildered bystander who’d only ever helped me. When we argued, I screamed that I never wanted to see him again, and I screamed it so many times that one night, when I called to change my mind, like I always did, he wouldn’t let me.
We met one final time, in a field off the highway. Buck’s Peak loomed over us. He said he loved me but this was over his head. He couldn’t save me. Only I could. I had no idea what he was talking about.