Lying to a friend to keep the peace usually just postpones the war.

Peace bought with a lie is borrowed, and the interest gets paid in how bad the eventual conversation becomes. The problem does not shrink while it waits. It gains the extra weight of having been hidden, so what could have been an awkward evening turns into a question about whether you can be believed at all. Pleasant and good are not the same condition.

Say the smaller true thing now, in the least dramatic words available, and expect a few strange hours afterwards. Lead with what you want to keep rather than with the complaint. A short uncomfortable talk is the cheapest version of this that exists.