Am I doing her any good, or part of the problem?

[PullToEject]

I spend time with my ex-GF of 4 months, (I am clear that I do not want an intimate relationship, we cuddle but do not have sex) maybe once every ten days or so.  Even then it's usually to go grocery shopping and nothing fun really.  I don't give her money but I'll buy her toilet paper, paper towels, juice for the fridge, and such.  I don't have much money so I think she appreciates that I do what I can do since she is struggling even worse financially.   

Thing is, we have what I think is a good day... .no arguments, we get stuff done, are good to each other and maintain the physical boundaries I have established... .then the next day she will be a miserable crying ball of tears all day.   Saying she misses me, she'll never find anyone that will understand her the way I do, can I please come over and hold her... .just really really really breaks my heart sad. 

Am I doing her any good or do I just cause he immense pain?  A big part of me says she needs a friend who understands (and will tolerate) her, but then after days like today I don't know if I am a net positive in her life or cause more heartache than good. 

Anyone else go through something similar?