Good for wife, bad for me

My wife wanted a soft mattress that felt like a cloud. At first she thought even this mattress was too hard, but after a few weeks she has come to like it. She also discovered that her tingly feeling was not related to the mattress but rather a separate issue with her hand that has been addressed. For myself, I'm about 160lbs and have recently been having back pain, both upper and lower. It got worse with this mattress, especially lower back pain. It seems I sink in way too far. My wife says we can't sleep too close together because it feels like she'll fall into my 'hole.' My lower back pain is unfortunately worse than before, and I believe it is because this mattress is not supportive enough for me. The middle of the bed feels better, where the saatva branded foundation has more support (because it's a king mattress so the foundation is split in the middle). Perhaps this mattress on a platform or hard surface would be better (their foundation is slat-based). One other issue is my chest, which has never been in pain before but now I wake up with a bruised chest feeling. Considering how soft the mattress is at the waist, it was surprising to me that it would cause this issue at the top of my torso. My wife and I really wanted to love this mattress but I think we will have to return it and try for something with more support .