I don’t necessarily see it that way. Would you still feel that way if Diana was Lily’s actual blood related sister? If my sister passed and left behind a child I would want to care for that child. Diana was essentially her best friend, and clearly someone she loved and cared about bug wasn't allowed to mourn. I’d do the same for my own childhood friend as well. If anything, I think she’s realizing that not everyone will simply assume she’s done all the because she’s romantically attached to Diana, but rather because she loves her like family. Felix recognizes that and that’s what is endearing him to Lily now.
They're not related by blood so it's not the same, but I understand your point, it still feels like a lavender marriage to me to some degree but I'm glad she's warming up to felix and I'll be more than happy if they actually get married
I've always shipped them but after 130 it kinda feels like a lavender marriage at least on lily's part...