Ruy Lupez

e4 e5

Nf3 Nc6

Bb5 a6

Bxc6 dxc6

Nxe5 Qd4

Nf3 Qxe4+

Qe2 Qxe2+

Kxe2

Is obviously bad for white because he can not castle his king stuck in the center where black can

Yeah, nobody plays Nxe5 if the e4 pawn isn't supported.

its not bad for white because he can´t castle, its bad for white because you play it entire wrong. the idea of the exchange spanish is to give up the  bishop pair for a pawn majority on the kingside.

Well yes black has a majority on the queenside, but because one pawn is doubled only white can creat a passed pawn and therefore has an endgame advantage.

so if you give black the e pawn there is no reason to take the knight on c6.

i forget the exact line, but the idea is for white to play d4 and exchange his d pawn for blacks e pawn.

I have taken the e5 pawn before I discovered Qd4