You might want to look up cognitive distortions. You seem to struggle with jumping to negative conclusions. All these things are fortune telling doom. Italics are mine.
You could choose tell yourself something else. Like...
New stuff is sometimes challenge enough. There's no need to add doom thinking to it and make it like a "double load."
What for? How does that help you get through it any easier?
Galagirl
- I have never ended a relationship, so it will be awful and I won't be able to cope.
- I have never seen Leo while he's in a relationship, so it will be awful to see them together (kissing, cuddling, loving looks) and I won't be able to cope.
- I have never shared Leo with a new shiny primary, so he won't be able to invest in our "old and boring, talking all the time" relationship. It will be awful and I won't be able to cope.
You could choose tell yourself something else. Like...
- I have never ended a relationship. So that will be a new experience. I will have to figure out how to cope.
- I have never seen Leo while he's in a relationship. So that will be a new experience. I will have to figure out how to cope.
- I have never shared Leo with a new shiny primary. So that will be a new experience. I will have to figure out how to cope.
- If he cannot invest in our "established talking all the time" relationship in the same way, I will have to bring it to his attentention. That will be a new experience. We will have to figure out how to cope.
New stuff is sometimes challenge enough. There's no need to add doom thinking to it and make it like a "double load."
What for? How does that help you get through it any easier?
Galagirl