A question about the Kings of Gondor

[The Squatter of Amon Rûdh]

this is probably why he was reluctant or afraid or unwilling to be king of Gondor.

On the contrary, Aragorn's becoming king of both Arnor and Gondor was a condition of his being allowed to marry Arwen. Elrond says to him in Appendix A of The Lord of the Rings

Many years of trial lie before you. You shall neither have wife, nor bind any woman to troth, until your time comes and you are found worthy of it.

Aragorn's entire life had been leading up to becoming the King, and he seems always to have been prepared for that position and ready to accept it. Only in the films is he portrayed as having doubts about ascending the throne.