Avoiding probate for unmarried couple

Marriage would indeed be a drastic step to achieve an estate planning objective, but it is not an unheard of event! Marriage may offer a lot of benefits, but avoiding probate is not one of them. Married couples have to plan to avoid the probate process in much the same way as an unmarried individual would.
 
Tenants by the Entirety is not an option for you, as you are not married. Joint Tenancy is, although as you observed adopting that approach would restrict your ability to later change your mind. If things do not work out for you as a couple, it can get very ugly, very fast. There are several approaches that might work - depending on the nuisances to your situation. My first inclination would be to explore the trust option. A trust would allow you to control the property during your life, avoid the probate process at your passing (for all property "owned" by the trust), and control the use and enjoyment of the property after you are gone. Just a note of caution, however. A bad trust can cause a lot of headaches. A bad trust that holds real estate is much, much worse than anything that the probate process will do to you. Talk with an experienced estate planning attorney and save yourself and the ones that you love a lot of grief.
 
Just think of the issues that you need to address: use of the property; care of the property; possible income and estate tax issues; repairs verses capital improvements; what happens if your significant other wants to downside or needs nursing home care. It really is a very tricky planning situation. But I commend you for your analysis and would encourage you to consider a properly drafted trust.
 
Attorney Peter Bernardin