If you are looking for representations of love and fate together, you need to look no further than lines 6 and 7 of the prologue. Both of those lines, taken together, strongly imply that fate plays a huge role in the play. Use of the term "star-crossed lovers" is a rather obvious reference to fate.
The stars are against Romeo and Juliet. The stars, in fact, are at cross purposes to the young lovers. Therefore, Romeo and Juliet are "star-crossed," and fated to suffer from circumstances beyond their control.
A less obvious representation of fate comes with the phrase "misadventured piteous overthrows." There is the sense of sadness (piteous), and tragic life-altering mistakes (misadventured overthrows). These events are beyond the lovers' control, and a strong representation of fate.
These two lines set up line 8, where the use of "fearful passage" and "death-marked" are used in direct linkage to the love between Romeo and Juliet.
Here in the prologue, we see that death is a foregone conclusion, and that the lovers are fated to die from their passionate connection.