Because we're tired of sending our tax dollars to one of the most corrupt countries on the fact of the planet.
...so funding was tied to illegals crossing our borders.
If the Biden crime syndicate and the DNC want to continue laundering money through Ukraine then they're going to have to stop allowing illegals.
If they stop allowing illegals then it shuts down their effort to grow populations in Demon-crat Congressional districts to effect reapportionment and the axis of power down the road.
“If the Biden crime syndicate and the DNC want to continue laundering money through Ukraine then they’re going to have to stop allowing illegals.”
I suspect from their standpoint they know that Ukraine is going to collapse anyway and even giving them money won’t help, since the Russians, Chinese, and North Koreans WILL NOT sell arms to Ukraine (and, of course, the West is unable to produce more than token quantities of weapons at this point), so any money going to Ukraine can be used to buy just about anything...other than weapons.
So, given the above, Obama likely figures that it’s worth cutting Ukraine loose now, if the price for keeping the money spigot going to Ukraine is a Secure Border, which is something that they can EVER permit.