My boyfriend is planning to move in my house, if the relationship doesn't work out after certain amount of time, will he own half of my aaets?

How are all your properties presently titled if not in your name? The short answer is that, yes, it makes sense to make sure that there is no uncertainty, no ambiguity whatsoever regarding what is yours before your boyfriend moves in.  It would be useful for estate planning purposes anyway for you to put all of your assets in a living trust.  You'll need to consult an estate planning attorney for help with that, but it would accomplish two useful things at once: making a record of what's yours and doing your family and friends a huge favor in the event of your untimely death or disability. Basically, the idea behind a living trust is to set up a trust and transfer all of your assets into the trust.  While you're alive, you're both the trustee and the beneficiary of the trust, and it really doesn't affect how you live your life.  When you die, however, instead of going through a long probate process all of your assets are immediately available to your inheritors, because everything is already owned by the trust.  The only things that change--and this happens automatically--is that you are succeeded in your role as trustee by someone you name in advance, typically a friend or a relative, and the trustee now administers the trust for the benefit of the beneficiaries you've named in your will.  It would be a good idea to do this now, before your boyfriend moves in, but what you're really worried about is a common law marriage, which results if a couple openly cohabitate for a period of seven consecutive years.