Also note: There's no such thing, canonically, as "Bionicles" -- Bionicle means a chronicle of life, or a story about biomechanical (and biological) beings. And in this context, as Taipu1 points out, not all Bionicle beings are the same in this way.
Anywho, might as well close this as question answered. Three main reasons:
1) Canonically it isn't debatable that Matoran Universe beings like Matoran do not have romantic feelings. They don't. (Note that they do "love" in the purer sense, however; as in brotherly love; wanting everybody to be safe, etc. and canonically the things you're confusing for romance are really that more pure kind of love -- close friendship -- as well as a mere political alliance in Sidorak & Roodaka's case.) Likewise, it's canon fact that Spherus Magna natives like Agori do. So there's really nothing left to discuss.
2) The makers of the semi-canon MNOGs and later online videos implying romance between some Matoran were likely not aware of what Matoran really were or the big secrets behind the story, as they did not clear much of that with the story team, which is a big part of why those are only considered semi-canon. (Note: it wasn't de-canonized -- common misconception -- because it was never canonized in the first place. The web team simply used some of their own interpretations and assumptions in programming the early online content.)
3) If the question is for fanfics, there's no need for discussion because people are already free to ignore the canon in their fanfics in general anyways.
Also, topics like this rarely go well, so it's best to just close it. It's a good question, but hopefully this is satisfactory as the answer.