Some horses are fine being kept by themselves because they either don't get along with other horses as in a herd setting, or they just don't seem to care and do fine with other company. My neighbor and friend has an old Arab mare that is in her late twenties and she does fine by herself. She used to have a POA that kept her company but he got sold and she seems to to be indifferent to it. Of course, she has attention from my friend and the three sheep and two goats that are in with her so that makes it a little easier, I suspect.
If your two geldings are excessively clingy and seem to really depend on one another, I would say that it wouldnt be a great idea to seperate them. You could also think about getting another companion for him, like a donkey, sheep or goat that would just be there to keep him company so he wouldnt have to be completly alone.
Shaneequah, 1998 gaited Bashkir CurlyxArab mare
Treyue, 1999 3-gaited Icelandic gelding
Loki, 2001-2015 Icelandic gelding