Another thing you can do now is use separate sheets and blankets if you're not already. That way if you roll with the blankets it doesn't pull the ones on him, and you can both cocoon up if you want to.
Temperpedic has a lot of stores with their mattresses so you could go see before you buy how well it works, and the website allows for full on returns if you just don't like it. They do take maybe a month or so to break in.
I'm 180 5'10, my wife is 120 5'1 and we both swear by the probreeze medium (tried the luxe but it didn't work). If you side sleep I'll link my and my wife's favorite pillow (takes about 2 weeks to break in, lasts maybe 6 months- a year before needing to be replaced)
If you find something else that works for you guys post back! The struggle is real for us too.
I think your issue (i had it) is you need something softer.
You can get a topper for a cheap option, otherwise I like the luxe mattresses from myessentia.
You could try another pillow too, i have tried a LOT of pillow cheap and expensive.
Ironically even though I am stuck with a ton of expensive nonreturnable pillows, my favorite for side sleeping is 30 dollars and returnable
Sealy Molded Memory Foam Pillow, Standard, White https://www.amazon.com/dp/B07Z6X6JCP/ref=cm_sw_r_cp_api_i_dc-EFbZR0T2R7
Coop was great but I coughed terribly on it.
Sealy Molded Memory Foam Pillow, Standard, White, Grey https://www.amazon.com/dp/B07Z6X6JCP/ref=cm_sw_r_cp_api_glt_i_WRYYPK0G1X7XTGA69FG7
I am too, mine started when I got a firm mattress but I've also gotten it when my mattress started hammocking too much.
I think you need to be able to sink in to the point that your hips are lower on the one side and higher on the other side of your feet. So your feet are between your hips, and your shoulders need to be a bit similar to your hips.
While I'm not a fan on sealy products I do absolutely swear by this pillow for side sleeping. https://www.amazon.com/Sealy-Molded-Memory-Pillow-Standard/dp/B07Z6X6JCP/ref=sxts_sxwds-bia-wc-nc-drs1_0?cv_ct_cx=sealy+pillow&dchild=1&keywords=sealy+pillow&pd_rd_i=B07Z6X6JCP&pd_rd_r=067e2909-e36c-4198-8fee-6f33fa64f4dc&pd_rd_w=qYG2n&pd_rd_wg=mEmAa&pf_rd_p=bb3ab43b-b104-4d0e-bd07-c0b6b72185d0&pf_rd_r=G5A6H97VCPBXF6NF3362&psc=1&sr=1-1-88388c6d-14b8-4f70-90f6-05ac39e80cc0
My wife, my father in law, my sister all sleep on it now plus you can return it if you don't like it. It takes maybe a week to fully break in.