Well she could have been wounded, treated but still in critical condition, then died in the room..... But I find each corpse getting its own room more amusing so lets go with that if anyone does lose their plot armor.
@boag not really. Magic here doesn't work that way
Growing back limbs is not doable using recovery magic. There are forbidden and forgotten spells which consume life span so even regenerating a leg would mean the death of the healer. Resurrection magic is plain impossible.
Masaru is already on a level where he can be considered among the top 10 healers in the world since he can use EXTRA HEAL and AREA HEAL, so other healers beg him *NOT* to learn such forbidden magic.
being on the cover doesnt mean they are automatically part of the harem. A certain girl was on the cover of one of the LN and that girl didnt join the harem but instead went for another guy who she meet after meeting Masaru. One of my favorite romances I have read in an LN.