Thinking about how depressing the first time Noodle was disappointed by Murdoc probably was. Knowing him... it wasn't that much later than when she met the band, but Noodle probably saw Murdoc as this cool, edgy, no-fucks-given rockstar. Until: she either saw him yell at Stu for the first time, or throw a girl out, or saw how weird his face looked while he was still actively taking amphetamines. It was probably crushing, and eventually, she'd learn to get used to that feeling.
I must admit, asks like this really make me think back on what exactly my characterization of Noodle is, and I'll be the first to admit that no character other than Stu and Murdoc has really gotten the full nooks-and-crannies treatment, so I find myself having two conflicting ideas of who young Noodle was. We see her act quite carefree, even giddy and appropriately childish in phase 1, and then that is significantly altered between phases 1&2 as she regains her memory. I think I tend to always see Noodle in that phase 2-3 era, and then make amends with some of the selfies and emojis onward, but phase 1 sort of gets lost in the shuffle. I do think Noodle's a highly capable child with more experience handling herself and the adults around her than most children, but she is still a child, and I do like to think the men try-- barely-- to shield her from things like drug binges and blatant objectification and disrespect toward the women moving through the house. Murdoc has no doubt been high around her many times, but Murdoc treats the uppers like part of himself, just a switch to "turn it on" so to speak; the first time he's tweaking and getting tremors while crashing on an especially bad trip, while no one has the mental fortitude to do much besides tell Noodle to go somewhere else, was likely pretty unsettling and left a twisty feeling in her stomach. The first time she sees him having a paranoid meltdown, snarling and snapping at Stu and not trying to reel himself back in when he sees her turns that twisting feeling into a leaden one. Like the rest of the band and parts of the audience, she eventually recognizes that Murdoc leans into his mania and unwellness as something funny, and it's easier at times to laugh or sigh and complacently play along with that than it is to really deal with him (particularly in the early years when he is so very resistant to "tampering" by frowning faces; knowing they're afraid, knowing they're pitying, knowing they think they know anything at all about him makes it worse. It dries whatever fun he's beginning to feel from companionship right up, and he turns thorny and escapist.) I am, however, a fandom criminal with a high bounty on my head because I tend to favor the whole found family and Murdad aspect a little less than most... not that I can resist it entirely of course, but I don't see any of them as especially good father figures, Murdoc least of all, and I think both of Noodle and Murdoc were keenly aware of that pretty early on. It's like... I do think she cares for Murdoc uniquely and Plastic Beach was a deeply scarring betrayal, but I don't think Noodle went into phase 2 thinking Murdoc was someone she could depend on.