I was actually thinking of several ways to make the love interest a bit more interesting.
For example: Gifts!
But, you don't just give your sweetie some standard items, oh no!
At certain times, probably determined by relationship and time together, a NPC shows up selling gifts, each of which boosts the stats/skills/exp of your love interest! Course, the items are delivered automatically, so the PC doesn't handle them directly.
Ah, but the love interest also give the PC gifts! I suggest the love interest give the PC gifts of items that are rare, such as amazing weapons, armor, or mecha items.
Also, the quality of the items should be inversely proportional to the quality of the lancemate. So, let's say you have a love interest who's a high stat, highly skilled Knight.
So, you get a handgun slightly better than average, as that lancemate is pretty good.
But, let's say you get a scientist as a love interest instead, who only has the basic mecha skills as useful skills, plus this scientist has lousy stats. Since you've gotten the shaft in lancemate, perhaps the scientist love interest create a mecha gun with scatter, brutal, and a decent DC?
Just my two cents.