If my boyfriend is married but put my name on his life insurance policy, can his wife stop me from getting that money after he dies?

Yes and no.  A person who ownes an insurance policy on their own life can list whom ever they want as the beneficiary of that policy.  But what comes in to play here is the right of a spouse to collect a certain portion of their dead spouse's estate and trying to set aside the policy designation.  I am not saying that she can.  But she might try.  So make sure she has enough assets to inherit if he goes. Good luck.