Artley has already explained it nicely, but I'll add my own thoughts too:

Issues in a relationship, especially within the therapeutic one, are not about blame. Rarely it's very clear who would actually be to blame. Of course, we like to blame somebody for all the problems, but in most cases it just doesn't work. People behave in certain ways due to so many factors, and many of them are not their fault. Maybe a certain kind of upbringing, or their genetics, or so many other things. And while there's situations where one should be very careful to keep their own factors in check, such as at work, in therapy it's almost the opposite.

You could think of it as a kind of black or white thinking, which is also rarely how things tend to be.

Yes, things about people with abandonment issues make them more prone to being scared by disagreement or unpleasant interactions. But that's just how it is, it's not the fault of anyone with these issues. It makes sense in that bad interactions may lead to abandonment and we try to avoid that. It's an automatic reaction and not something you can affect too much, and reacting to anything that's perceived as abandonment will happen pretty quickly, at least for me. You can learn to manage that, and you're trying to do that.

I wouldn't blame somebody who got triggered by fireworks with the family, ran inside dropped to the floor, maybe tried to attack somebody else. I don't think people with other kinds of issues are to be blamed for the same reasons. In therapy, only one side really shows their issues, so it seems one-sided, but that doesn't mean it's not okay to have these instances.

Of course, this means that there will be maybe more issues than in other therapeutic relationships. But with a T like L you can look at it as practice, she doesn't just up and leave when you express your issues, she agrees with your instincts if they are correct but hopefully also is there for you enough that still have the support you need.