What does 與 mean in 對我來說她的存在是與現實之間的邊界綫?
對我來說 - to me,
她的存在 - her existence
是 - is
???? (object A - missing )
與 - and
現實 reality (object B)
之間的 - that between
邊界綫 - the borderline

[1. 對我來說] [2. 她的存在] [3. 是] [4. X] [5. 與] [6.現實][7. 之間的] [8. 邊界綫]
[1. to me] [2. her existence] [3. is] [4. X][5.and] [6. reality][7. between] [8. the borderline] (Chinese grammar)
[1. to me] [2. her existence] [3. is] [8.the borderline] [7. between] [4. X] [5. and] [6. reality]  (English grammar)

X could be something opposite of reality , e.g. &quot;dream&quot;, &quot;fantasy&quot;
&quot;Her existence is the borderline between dream and reality&quot;
X could also be 'I' meaning if she didn't exist, I would have to face reality