i think the ghast ball traveled and hit your portal breaking it, so when you went though the one in the nether i think it made another portal because there was no portal lit on the other side
nether portals will link within like a 60 block area, to fix your "bug" you need to take your portals location and divide by 8 then put a nether portal there in the nether
i think the ghast ball traveled and hit your portal breaking it, so when you went though the one in the nether i think it made another portal because there was no portal lit on the other side