I actually do treat my closest friend more like the former; we've been friends for 10 years so it would be strange to not feel like sisters at this point. Our friendship is pretty deep and intimate.
On the other hand, it depends on the friend. Not every friend can be seen as family as you might not know them long enough or trust them enough for them to be that high on the priority list yet. I am an introvert (and a pretty extreme one at that) so I don't really have the time or energy to manage a bunch of friendships on the same level. I like a select few that can fit the former, but It'll take time to get there. On the other hand, I do agree with you that it absolutely sucks when friends are replaced by SO's. In many ways our friendships can be even more important; at least to me they are.
On the other hand, it depends on the friend. Not every friend can be seen as family as you might not know them long enough or trust them enough for them to be that high on the priority list yet. I am an introvert (and a pretty extreme one at that) so I don't really have the time or energy to manage a bunch of friendships on the same level. I like a select few that can fit the former, but It'll take time to get there. On the other hand, I do agree with you that it absolutely sucks when friends are replaced by SO's. In many ways our friendships can be even more important; at least to me they are.