He might get more invites, but the reason he's coming is desperation. If Trump wins the US election in November, then Ukraine's munitions support and intelligence gathering support will drop by 50+% on the 5th January. Zelensky has this summer/Autumn to get the Russians - effectively - out. There's a good chance (though quite the exact nature of that chance I don't know, because I'm not an expert on US domestic politics) that the lines that Ukraine manages to achieve by late November are going to be the lines it has to live with.
And, obviously, he knows that he's not going to know if November is his last throw until November - which means he has to get as much done as humanly possible.
To an extent, he's pushing against Schrödingers' door, it's both open and closed. Open because the rest of Europe see's the same thing, but closed because Europe also suspects, with good reason imv, that if Trump becomes president in January, he will effectively withdraw the US from NATO, which means that Europe will be on its own, and that each pallet load of 155m artillery shells that are sent to Ukraine, means a pallet load less for them if shit goes bad.
Squeeky bum time.