<human>: We were together a year & a half, got engaged in September, amount of sex decreased.  Otherwise, everything is amazing and this person is the most awesome person and my best friend.

I've brought it up twice with fiancee.  First time was just a, "is everything okay?  just curious if anything is wrong/making you not wanna have sex..."  and it was kind of shrugged off and dismissed as there was nothing wrong, but the lack of sex persisted.  Second time (about 2 months later) was a bit of a bigger deal - I straight up asked if she was still attracted to me, she said yes, she just can't get right back into it if we aren't spending quality time together.  So I asked what quality time was to her to clarify (I didn't consider the time we were spending together not quality time), and have tried to do more of that, though it's been a bit hard with our schedules.  Nada.  

I was hoping it would just kind of get back on track, but it's yet to happen, and I find if I don't initiate (which I haven't in a while now), she doesn't, and I'm scared I've created a stigma around it to derail it even more.

She was planning on being away this weekend and I came home from work and playfully asked if she wanted to have sex before she left, but when I got there she had already masturbated.  Obviously if our sex lives had been normal it'd be a whatever moment, but my chest got tight and I felt perturbed.  

I'm not really sure the best way to deal with this now that won't make it a big thing.

Can you summarize the given text in a few sentences?
<bot>: sex dropped off from 3-4x's/week to 1-2x's/month.  how do i approach without creating more stigma?