Question

All my attempts to make him happy proved...................... This is fill ups

Answer 1

All my attempts to make him happy proved worth it

Hope this helps ✌

Answer 2

Answer:

Futile

Explanation:

This sentence gives negative connotation . So, Any Negative Word that fits the statement would be appropriate and out of this, Futile would be the most appropriate word.  For Example-

Ukraine's negotiations with Russia would likely to be futile if Ukraine doesn't fulfill Russia's demands