What do you guys do to prevent the onset of oneitis in a LTR

Of course, by definition you can't have abundance mentality if you only have one woman, even if you keep the mindset, the reality is that you only have one sex supply, so it better be reliable.

Some guys can pull it off, it is difficult, but doable with good dread game. Even if you're exclusive, you want her to keep in mind that you can attract women, and she can be replaced easily. However, most guys won't be able to maintain that in the long run.