If you enjoy both, that's even better but sometimes (I've found) when people make two threads, it's said up front each writer prefers x/y thread over y/x thread but I'm glad that's not the case since it makes things less complicated.

But you need to tell her what's up! She's clearly not taking a hint so just tell her you want more love in the second thread, it doesn't need to be emotional or anything, just a gentle nudge might be helpful for them. Say you like both but feel like she's constantly dragging her feet with the other thread, maybe due to lack of confidence or comfort but that you want more progress? Would that be possible?