My nether portal teleports me to the overworld coordinates not the nether portal coordinates

In my minecraft overworld I have a portal to the nether, for some reason instead of taking me to the portal in the nether like its supposed to  it boots me to the coordinates of where I was in the overworld, (I play with cords on) and the first time I was stranded but the second time a new portal opened behind me. When I left I was over 100,000 blocks away from my base. It's really annoying as this is the second time this has occurred, I dont know how to prevent or fix the issue other than walking all the way back. Please look into the issue if you have time. Thank you