I think your question was answered thoroughly in the previous thread that was closed. The vast majority of Catholic members clearly state the answer is “no” with regarding to sharing the same bedroom with your fiance, and offered a variety of alteratives to this arrangement (ie. sharing a room with your brother, having your fiance share a room with your sister, getting an air mattress, etc.). The members of the forum mentioned that factors such as sexual temptation and the threat of scandal as being sound reasons for avoiding the arrangment. The Catholic Church does not micromanage when it comes to each individual’s circumstances-- thus
“no sex before marriage” is the clearest we will get. However, the experienced members of the forum are telling you that it will be extremely difficult to maintain chastity while sharing a bedroom with your fiance. Right now you do not share a bedroom with her, so you can assert that you will be “ok” and be able to avoid the temptation. BUT when the temptation is right in front of you, or the circumstances make it easy to sin, it does happen, even when you don’t mean it to happen. You may not have sex with your fiance, but you might engage in other sexual behaviors that are sinful for unmarried people, mainly because you are sharing a living space, and if you have any level of attraction for her, there will be a likehood of sin. AND, you do not mention whether it will be easy for her to share the living space with YOU!! (You might have the strength to avoid the temptations, but what about her??) There is more to avoiding sexual sins than just not having intercourse!
I did not live with my husband before marriage, and I think it was the best decision. We experienced the joys of living together and sharing a room after our marriage, a right that was bestowed upon us when we exchanged vows and made that committment. I think the other members are right in that you need to make the right decision. If you must live in the same house as her, ssk your parents for help in arranging your home to best suit separate rooms for you and your fiance.