Conversationally and narratively speaking, "offer to make clothes for her" is an awkward non-sequitur. It's slightly weird.
Offering to make somebody trinkets or metal stuff has different connotations compared to offering to make clothes. It's more intimate because it's something you wear rather than an accessory or something you wield like weapons and armor. (Yes yes I know, mages and priests and etc wear cloth. You'd be missing the point though. Clothing is used, and seen, differently from armor.)
Maybe if we offered cloaks or scarves, it wouldn't be as "Wait what?" as just offering to make clothes in general.
Offering to make clothes for somebody who, basically, moved in with you sounds awkward, basically.
I'd like some clarification from Lost Star on the Jewelcrafting point -- are we already good at it or what? -- but I'm more interested in it because it's something that can directly go on our weapons and armor.
Whereas Tailoring is... sort of outside what we normally do. While Jewelcrafting nicely works itself into the things we already do; hence, if Jewelcrafting is something that can be advanced, then doing so would benefit.