Is the husband sinful for causing his wife sadness due to the strained relationship between them, despite providing her with all the necessities of life, being kind to her family, and intending to perform Hajj and give charity on her behalf and maintain ties with her family?

Allah has commanded the husband to treat his wife with kindness (ma'ruf), and this includes honoring her, speaking gently to her, fulfilling all her rights, and refraining from harming or abusing her. If the husband's aversion to his wife does not prevent him from fulfilling her rights and not wronging her, then there is no blame upon him, for matters of the heart are in the hand of Allah. What you intend to do, such as performing Hajj on her behalf, endowing a waqf, giving charity, and showing kindness to her parents, are all acts of righteousness, goodness, and loyalty.