This may seem really, really bad, but I trust the mangaka enough to believe that this won't lead to a breakup or anything. It actually feels like the push Mitsuki needs to finally talk to Aya instead of avoiding their issues like she's done in the past.
I'm pretty sure the jealousy was an act to scare the Tanuki away from pursuing his wife, since he doesn't see any life for himself outside of his marriage to her.
My thoughts exactly. Lives in a weird tech shack on the outskirts of town, turned herself way too young, is actually an attractive woman when fully grown.
It's more likely to be 316L stainless steel. Titanium has really strong osteointegration and wouldn't be used for fracture fixation.
Source: I'm a biomedical engineer.