I started a phD in October 2015 and got the impression I would soon be able to upgrade from Mphil. My main supervisor has generally been quite happy with my work but my second supervisor has said once or twice he doesn't think one of my areas of argument is worth pursuing but he's not always been able to give FB on my drafts or come to meetings so I've just carried on with my idea.
Last week the second supervisor said I definitely should give up on this main topic. This is really annoying because I've spent a long time and written 35,000 words on the topic. I honestly think it's a reasonable and quite well argued idea too. I suspect he wants me to avoid it as it takes a critical approach to a field his wife works in. My main supervisor doesn't seem to feel strongly but did not disagree openly with him at the meeting.
I was due to upgrade in the next couple of months but will now have to start writing more or less from scratch again and abandon my idea which I'm very attached to.
I am wondering whether to approach a different supervisor at another university and transfer there? Is this an acceptable thing to do. Have other people done it?