> If I'm burning my hand on a hot stove, I don't want pain killers to mask the pain.
If someone else's hand is on a metaphorical hot stove, while I agree that it's acceptable to offer a third-party opinion, I also don't think it's acceptable to deny the person painkillers just because we think it's better to just get their hand off the stove. Sometimes you don't have the option of freeing your hand right away, and at least in the meantime (however long that lasts) some painkillers may be a lifesafer.
* I take your example metaphorically because active, serious self-harm is an exception to usual norms. One would likely jump to remove someone's hand from a hot stove without thinking, but even taking away an addict's cigarette or drink would generally be a faux pas. Having an AI that allows you to fall in love doesn't fall in the active self-destruction category, in my opinion.