Does Romeo truly love Juliet and why?

In Shakespeare's Romeo and Juliet, the love affair between the two teenagers is not meant to signify a story of true love, but a story of silly family rivalry that has driven a well-matched couple into such desperate straights that they kill themselves. So, no, Romeo did not truly love Juliet, but simply loved the idea of a beautiful woman he might marry.

The first time we see Romeo is when he is pining...

In Shakespeare's Romeo and Juliet, the love affair between the two teenagers is not meant to signify a story of true love, but a story of silly family rivalry that has driven a well-matched couple into such desperate straights that they kill themselves. So, no, Romeo did not truly love Juliet, but simply loved the idea of a beautiful woman he might marry.

The first time we see Romeo is when he is pining over the loss of Rosaline to "Dian's wit." While many English teachers seem to suspect this has something to do with Rosaline choosing a life of service to the church, there is no evidence of this. Instead, it seems as if Rosaline rejected Romeo's sexual advances and he says that this is due to some vow of chastity she made.

With Shakespeare's early indirect characterization of Romeo in mind, the next real glimpse at him is at the Capulet's party when he sees Juliet. While Romeo has no idea who she is, his view of her from afar causes him to pine after this girl who has "Beauty too rich for use, for part too dear." And then he stands and watches her. In his very first conversation with her, Romeo does not attempt to know her as a person and, thus, fall in love. Instead he asks her, "My  lips, two blushing pilgrims, ready stand to smooth that rough touch with a tender kiss."

This infatuation Romeo has with Juliet is aided by two adults—Friar Laurence and Juliet's nurse—who encourage the marriage between the two children. The friar specifically states that this marriage could "turn your households' rancour to pure love." 

It is worth noting that Romeo's passion for Juliet, including his suicide, indicate some level of love. However, this is love that is not based off actual knowledge of Juliet, but love that is based off teenage sexual desire and Friar Laurence's  manipulation of him for his own political purposes.