Given Stews comments, I doubt it'll be a hard dropping hammer unless you screw around after committing or with some of the side LIs a main LI hates.
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If The Author is any indication, it'll likely be a much softer resolution of picking which LI or throuple (of which there are two possible) to commit to.
Edit: You can actually have committed to Kana already. Doing that and then still fucking around likely will have consequences.
I do also think you might get a "softer landing" if you really only do stuff with the main LIs, and aren't quite as aggressive to have sex as soon as possible but wait until the second or third opportunity when the LI is the one to initiate it.