That’s actually a pretty interesting take on Bern’s character. Ryukishi often delves into the darker side of selflessness, and it makes Bern even more sympathetic and a bit tragic if you can see her agonizing over the fact the fact that she had to give others happiness, while forever being denied hers.
If I was in her position, I would certaintly almost feel hesitant at making someone happy if I couldn’t for eternity.