Came here to say something similar, as I feel the OP's "fall apart" comment too. However, my bigger anxiety is not that it'll "fall apart", but that things will "fall apart" and then it'll be my role to fix it.

If I died, I don't care.

If I left the project entirely, I don't care. I've moved on many times over my career. I can live with that.

But... if you leave early for a bit, then things "fall apart" and you have to then fix things.... that is the bigger concern. It's the 'fix it' part that bothers me.

Timebox your contributions and ensure you work less hours according to everyone. Even it it falls apart, you work for those hours to fix it. Then you leave. Who cares if it breaks more than you have time to fix? Nobody will die (probably) and everyone at that company gets paid to pull their weight. Time for them to do so.

This has been my experience. It became an expectation _of my peers_ that I am the one who should step in to fix stuff when it breaks as if Im the sole owner.