Maybe her progressively getting 'more and more miserable' and looking on the 'edge of a nervous breakdown' is because the biggest evil she has ever come up against is ramping up throughout the season, her home is being taken over by a nonstop stream of young girls whom she feels entirely responsible for who keep dying, she's trying to figure out how to be a General, a role that is antithetical to
being the Slayer, her own Watcher is going behind her back and trying to get the person she feels '
has her back' killed, is leading missions where one of her best friends is severely injured and several more girls are killed, and is
kicked out of her own house, a decision that is supported by literally
everyone including her
best friends, sister and father figure, for proposing a mission that she ends up
being right about.
In the comics, Buffy is not 'guilted' into a relationship with Spike. She pursues
him and he initially turns her down and for good reasons that show him prioritizing himself and his own heart's well-being over Buffy and her feared-to-be-fleeting desires. When he does decide to enter into a relationship with her (after a conversation with
Xander of all people) they have any number of yes, healthy and mature conversations about their relationship and their past (including the sexual assault which is given more time and care than the show gave it) and the reason I absolutely bought that they could get to such a place in the first place is because of the foundation that was built in S7. If you were referring to S7 however and I misunderstood, Buffy's not guilted into a relationship there either, she chooses to help Spike, she chooses to support him and invest in him and later depend on him. No one is making her do that, certainly not Spike who at one point tells Buffy she should kill him because of the First's hold on him and at another point offers to leave because the First isn't done with him like they thought. She's given outs re: him and she chooses not to take them every time. She has full agency here. There are any number of reasons why she chooses to engage with him and in the ways she does, and guilt may play into it to a degree, especially in the beginning, and I'm sure it does, but that is not nearly all there is.
As for the feeding, I don't remember it being portrayed as remotely ok at all. The situation was f*cked up and neither of them wanted to do it or were comfortable with it. There's a whole thread discussing it here:
Feeding Spike