Sex with my wife

My wife has asked me to initiate sex because she's uncomfortable with the idea of sex. When I bring up the activity, she wants to schedule it out for a future date like a calendar appointment. I bring up the idea once every couple of months because I'm trying to respect her boundaries and I can control my urges (no porn). We've been married 2+ years and the last time we had sex was maybe 6 months ago.

I'm fine with not having sex all of the time. I just find it frustrating that I've been asked to initiate the subject and then feel like I've been rejected when we schedule it out like a doctors appointment.

As an example, I asked this afternoon (Sunday) when we didn't have any plans for a couple of hours (not that it takes that long). She then suggested that we make plans to do it Friday night.

Is this normal in other marriages? Do people plan out their sex life with appointments? Is there another sub that this is appropriate for?