The claim and the accusation in the same breath
The speaker calls God 'my God' twice in the very moment he accuses God of abandonment. The possessive does not soften before the charge lands. Both stand at full strength, side by side.
When a relationship has broken down, ordinary speech distances itself first. A person who feels betrayed stops saying 'my friend' and starts saying 'he' or simply 'you.' The possessive quietly withdraws before the accusation steps forward.
This verse does not do that. The speaker does not pull the claim back to make room for the charge. 'My God, my God' — and then, without a loosening of grip: 'why have you forsaken me?' The word 'my' is still there when 'forsaken' arrives. Neither term yields to the other.
The verse would be easier to hold if one of them gave way. If the speaker had said 'O God' — the relational claim released, the accusation a cry into distance — the tension would drop. If he had said 'my God would never forsake me' — the accusation dissolved into trust — it would drop the other way. The verse does neither. 'My God' and 'forsaken me' press against each other in the same line without resolution, and the verse simply stops there, holding both.