Expired I-94 is not a hindrance to getting married.
There is no entry ban based on nationality. OP, a Belgian national, is currently* visiting the US, so that is more than sufficient proof of my first sentence. You can also read the relevant proclamations to confirm.
*Presumably OP went to unrestricted country (e.g. Mexico, Croatia, Serbia, Turkey, South Korea, etc.) for 14 days before attempting US entry.
MagyarUSA reacted to HRQX in Withdrawing k1 and getting married on ESTA then AOS