How are Romeo and Juliet doomed from the start, not only by fate but their own personalities and people that surround them?

Romeo and Juliet suggests that individuals are often hamstrung by the identities forced upon them from outside. Most notably, this theme is manifest in Juliet's balcony soliloquy, in which she asks, "Oh Romeo, Romeo, wherefore art thou Romeo?" (2.1.75). The central obstacle of the play is that the two passionate lovers are separated by a feud based on their family names. The fact that their love has little to do with their given identities means nothing to the world around them, and so they must choose to eschew those identities while they are together. Unfortunately, this act of rejection also means Romeo and Juliet must ignore the world outside their comfortable cocoon, and, as a result, the violent forces ultimately crash down upon them. A strong sense of identity can certainly be a boon in life, but in this play, it only forces separation between the characters. Even Mercutio, who is not actually a Montague, is killed for his association with that family. The liveliest characters in Romeo and Juliet die not because of who they are, but because of the labels that the outside world has foisted upon them.