The ending is ... interesting.
I can't remember what I thought when I first read it, but as I was very young I probably thought Tarzan had just had a narrow escape from servitude and could now swing back to the jungle where all the fun was to had
.
But looking back now, I think the ending was inspired - pure marketing genius. It gave this first book an acceptable (to many) conclusion but still leaves that dangling hook to bring you back for "The Return of Tarzan", "The Beasts of Tarzan" and then ... "The Son of Tarzan"! So you know Tarzan's going to get some payoff eventually.
As for any romance to the romance ... I think we're supposed to accept white nobility calling to each other across the void of language ... combined with some animal magnétisme.