selling your portion of the title

I guess it depends on the set up of the mortgage.

Divorced people do it all the time.

Quite a few of my friends have "bought out" their ex-husbands (effectively buying 50% of title)
is it possible, that you can sell your 50% share of the title?
Yes, if you are 'tenant in common'. If you are joint tenants you both technically own 100% of the property and your 'share' is indistinguishable. In that case property gets transferred as a whole to the new owners, though one of them might be your partner. Not nice from the stamp duty point of view, not to mention paperwork.
Thank you for the replies, in tenant in common situations, has anyone bought the share where its not in a divorce situation? I guess I never seen it advertised, but it should be able to?
Do you mean buying your partners share that you are 'tenants in common' with? If so, I would think this might incur a CGT even and also stamp duty.
Yes, I have purchased a partners share of a property - stamp duty payable by me and CGT by them, and legal fees, loan fees etc.

Don't think you will ever see these advertised. The remaining partner wouldn't be happy to accept a stranger nor would the new partner accept an existing one they didn't know. With the loans both parties are jointly liable - if one doesn't pay the other must.