Yes, having Ivy involved with Holly switches off trinity route:In this playthrough, it is an Ivy dominant corrupted Holly so I'm guessing it's somehow related to that.
Python:
l "Thank you so much, Holly. I really value your opinion. You're a great ally to have!"
h "I'm so glad you trust me enough to make me part of your creative process..."
//...
elif v8_holly_sex == "ivy" or v8_holly_sex == "lenaivy":
if lena_go_holly > 3:
$ lena_go_holly = 3
Python:
if holly_ivy and lena_go_holly > 3:
$ lena_go_holly = 3