Your fear is misplaced: both projects are like my children and will be completed with the utmost care.
I've been writing stories for over ten years and I've never not finished them/one has never taken the backseat to another.
A little under a year ago I started writing both stories at roughly the same time and I have been bouncing back and forth from the outset. This is common practice for creative projects and releasing both games side-by-side has been my plan from the start. The reason I made the decision to partner up with Alorth and create Radiant now (instead of a little later) is because I'm very close to being financially able to leave my job (I currently work about 36 hours a week, down from 57).
The extra boost I will likely see to my income from Radiant might be the boost that helps me do this full-time... which means I will be able to update Polarity faster... not slower. I work three 12-hour shifts per week, and by the time I get home I'm too tired to work on the project efficiently. Radiant will allow me to possibly add three extra days to my game development schedule each week... and because Alorth handles the artwork & animations, creating it consumes very little of my time compared to Polarity.
As for the bit about you wanting to see a completed project: that doesn't happen overnight or at the snap of a finger. Every decision I've made thus far has been a calculated effort to get updates out faster to you guys, but unless y'all want me to just throw 20 minute updates together once per month without much thought put into the story, game design, and overall creative effort... it's a slow process.
The level of care I put into these projects is why I sometimes get hung-up on the updates near the end. The game might be coded, written, and mostly shot... but I'm not going to release it to anyone unless I'm truly happy with it (and know you guys will be too). My Patrons understand this/prefer it that way and I've communicated these things to them on multiple occasions for transparencies sake... despite literally slaving away and rarely even sleeping in order to balance the game, my normal job, and the other time consuming responsibilities I must tend to each month which I haven't even touched on.
But hey, maybe if you state the obvious again the game will magically be done sooner.