That is partially true. Putin doesn't trust the West, as we have reneged on every agreement regarding previous conflicts (such as Minsk 1, Minsk 2, and the issue of no eastern NATO expansion if you want to go back further). I think once he secures control over the Russian-speaking regions of Ukraine, he may agree to a treaty, provided that Ukraine remains a weakened state with limited power. That's just realpolitik.
In the war of attrition, Russia has the upper hand. Russia is stronger militarily than Ukraine in every metric: production, military technology, and personnel.
For example, Russia is now producing over 5 million artillery shells a year,
while the US can barely produce 360,000 a year. It's a significant disparity.
Another example is the cost of manufacturing artillery rounds.
It costs a NATO country between $5,000 to $6,000 to produce a 155-millimeter artillery round, while it costs Russia around $600 to produce a comparable 152-millimeter shell. Oh, never mind,
it's actually 8,000 Euros now.
We can discuss the root causes if you're interested, but your argument to "keep supplying Ukraine until Russia eventually breaks" seems wishful thinking.