In tarot cards, does the position of death only mean bad luck?

No, real death means "end". It may be the end of a relationship, or it may be the end of a relationship. Or it could be the end of something. If you are divining that a couple has a proper death, it is not necessarily the "ending" of lovers' separation. It may also be the end of a certain stage, it may be the end of their lovers' identity and husband-wife marriage.

Death by hanging upside down means "beginning". This may be the beginning of a new life. Or it could be the beginning of something bad. You should take precautions. Therefore, the card of death is not a very certain bad card. It depends on the relationship between your deck. Also depends on the actual situation.