I have started writing this story that has been brewing in my mind for the past few months. The problem is that it has paranormal/fantasy elements that will come into play later in the novel after a particular character's death. My concern is that I will need several pages to establish the bond between the readers and said character for her death to be meaningful and I'm scared that by the time I achieve that goal it might be too late to drive the narrative in a completely new direction. The first part of the novel is about the life of my protagonist and will focus on the relationships he has with his friends while the second part will be a quest for redemption complete with fiends coming from the depths of Hell itself. Do I risk misleading my readers into believing this is a romance novel and then be shocked when the story starts to gravitate towards fantasy and paranormal? Maybe I should use foreshadowing and subtle elements earlier in the story the set the tone.
Yep, I think you've answered your own question. Either go for the whole foreshadowing or eeriness thing, or you could try another technique I've seen used. Make the prologue a flash-forward into the middle of the supernatural action and end it with a cliffhanger. Then proceed with the story as you had initially planned. The prologue doesn't even have to be from the MC POV, you can use a minor but slightly interesting character.
Or you can pull a bait and switch over readers Like for example take Uncharted: Drakes Fortune, the whole game is this Indiana Jones-esque thriller with lots of shooting and action and halfway through the game switches itself into a monster filled shootout with Demons under an Evil Spanish curse and then puts in these nice creepy sections where you're desperate and alone. It actually can pull the reader in further with the surprise, renewing its freshness.
I'd be willing to read this no matter what style choice you chose. Maybe write it the way you want, without worrying about the betas, and figure it out later in edits, or after a beta type reader/ critiquer has given you an opinion on the switch.