Not Having Any of It
For some males (not all), there is a sense of pride in being the one to end their relationship, rather than the other way around. Some women are also like this, but not everyone is. Anyway, what I’m getting at is that it’s something like that.
The boyfriend desperately wanted to be perceived as breaking up with his partner, but she wasn’t having it. This may very well be the case when you try to end your relationship via text.