It is not a problem to live with some family members and don’t share the same bed (and important too, you should not share the same bedroom). It car realy EASY be done! Trust me! If have done that. If your family know before, it would be easier, because they will not ask why you don’t share a room.
But sharing a roof now as you are both discerning marriage, and not sure what to do, isn’t very smart. You seems poorly compatible now. You will not be free to end the relationship, because it would means putting this boyfriend outside one day. He would be dependant on your charity, and breaking may not happened, and a marriage for the wrong reasons, yes.
You have to be very clear with yourself why you want to be married. We married because it is a sacrament for all life for a conjugal life. Not for a big party. Living together outside of marriage is a sin, and it is out of question.
And of course you should be agree with what a catholic married life would be. Sexuality, openeness to have children etc.
Hard premarital counseling is advise to understand if a married life is possible for both of you or not.
