Legal Question in Real Estate Law in California

Very, very doubtful.......tenants can be evicted for illegal drug use, and the Feds sometimes sieze property owned and used by dealers, but I do not know of any law or principle on which an owner can forfeit ownership for a guest's recreational use of pot.

Of possibly more concern is the arrangement, if any, under which your wife has possession of your house. It sounds like (a) you are the sole owner of the house, i.e., it is not community property, and (b) your wife's right to be in possession is based on some rather casual deal, not a lease or something like that.

I would suggest that before this informal situation develops greater problems, such as under-maintenance, a suit against you for an injury to the guest, etc., that you either sell the house or make the lady's presence there somewhat less irregular by getting a lease in effect, even if the rent is only a nominal $10 a month.

Make sure it stays insured, is maintained satisfactorily, and the taxes and HOA dues (if any) are kept current by someone. Also, is there a loan on the house? Who must pay?