Nothing to do with George Galloway but those Labour MPs who have defected were ALL in favour of recommissioning Trident (cost 200 billion and rising) and against an investigation into Tony Blair's part in the Iraq War. This is all known fact, not hearsay.
And it could be why they feel the Labour Party is no longer one they want to belong to. Also, they could be deselected because they no longer represent their local party's views on defence etc. And now they can, and will, no doubt, join another party or stand as independents.
This nothing to do with bullying, it is part of the democratic process!