Expeditious retreat isn't a ritual spell. It's also intentional that you can use other spell slots for warlock spells.
Sanctuary I believe is intentional. It makes sense to me at least that you can't claim sanctuary when still intentionally harming people. The attack that caused the damage over time was made with intent to harm. That intent is still there when the harm happens, so you've broken sanctuary. And we're talking about a situation that involves divine magic and beings who can tell your actual intentions.
Unfortunately, unlike tabletop there's no way to really argue about intent (accidentally hitting someone with splash damage for instance), or roleplay a change of heart mid-combat. So for that and mechanical reasons, it makes sense to me to just have it break on any damage.
