Girlfriend says we're too different

[optimism]

Hello everybody.

For the past four months and a half I've been in a relationship with this girl who has a real mess in her brain. Ever since the first month together she would sometimes randomly say that we're too different, that we have nothing in common, that she feels like she can't do anything when she's with me because whatever she likes doing, I don't (but she never tries asking beforehand...).
This has come to a point where we spend a great time together, but whenever we're apart, every two days - or even every day - she would start over saying that she's not the right person for me, that I'm better off without her, that I should better find someone who is more similar to me and such. It's then a long quarrel until I finally stop writing and, after 2 or 3 hours, she writes back, slowly going back to the "I love you so much" phase.
Yesterday it all happened again, so after work I went to her place and we talked a lot. She said that she can't imagine a future together with a person so different, and that she'd rather be single because when she was she didn't have such problems. I told her, with an old Italian proverb, that "who doesn't do anything, doesn't make mistakes - yet doesn't do anything", at which point she kissed me out of nowhere with a very passionate kiss at the end of which I asked her: what did you feel? She answered "nothing", but then proceeded to kiss me again ("nothing" is her filler word when she doesn't want to answer, of course). To cut a long story short, we didn't have sex only because her parents were home, but that was the plan.
So we go for a walk, get ice-cream, then I go home. I wake up this morning and send her the usual "good morning <3" text, to which she replies enthusiastically, we make plans to meet at 2pm (which is the time at which we usually meet), then she starts moving that forward and forward all the way to 3:30pm. Nothing that strange, but when I ask "will we cuddle when I get there? <3", her answer is "yeah". She then goes offline and doesn't reply anymore. That's the sign. She's having those thoughts again. She's denying it now, but I know she's having them.
What should I do with this girl? I really love her and I know she loves me back - when we're together there's no way I could mistake that for anything else. But lately this whole thing has been a heavy burden to bear. I think her doubts are related to the fact that she's never really had any boyfriend before, and she said more than once that this whole love thing is so new to her that it caught her completely unprepared - it's something so big she doesn't know how to handle it. Therefore I'm kinda sure that even if we broke up she'd never really be comfortable with anybody else, and that would lead to pain for both of us, she'd feel guilty and try to come back to me, which would be even more painful. I know this is one big "slippery slope"-thing, but I know her well enough to say this. The most she's ever been without hearing me is 5 hours (excluding nighttime) and she totally went crazy for that. What should I do to make this relationship work the way it's supposed to?

[breathe123]

Sounds like she is insecure or maybe has depression. Is she on any dr prescribed medication? What do your friends say?

[hazey daisy]

I agree she has signs of a mental illness. Her confusion with her thoughts and emotions is very telling. My advice is to suggest to her see her family doctor to get a proper diagnosis. Either that or walk. Left untreated, it will only get worse, and the possibility of suicidal tendencies.

[LunV93]

I think she is very insecure, maybe a little depressed. I also have an insecure depressing boyfriend, and what I've learnt is that you can't change the way that person feels. It is exhausting and sad and she is hurting you when she feels depressed.
I know you are in love and that you want to fight this for all those good times together (believe me, I'm in a similar situation), but you could do what she says next time she has those feelings and let her be single, then she might appreciate you better (that's what lots of people have told me to do).
Honestly I think you deserve a person who fully appreciates you, who can see how wonderful you are, not a girl that thinks you two are so different and that she can't do all the stuff she likes with you. You two have been together for just 4 months and she is having these bad and depressing thoughts, you two should be so happy having fun these first months together. It's hard but those problems might never desappear, you could continue having these kind of conversations with her for months.
You could try to have a conversation with her, tell her what you feel, and try to come up with a solution to stop these kind of things. With the time you will see if it works, and if it don't, you'll know what to do.