For those who are unsure as to what happened, basically Eris is feeling like she needs to mature more and become someone more dependable and capable, and thus she meant that by when she said they're not matching as of right now. Eris was never one to be great at communicating clearly, and thus her very terse and vague letter. If it was purely just sex incompatibility, she wouldn't have cried like that during the night. She loved him dearly, but realized that she needs to get stronger first before anything (at least that's what she believes is best). And in Asian cultures, cutting your hair like Eris did usually means a season of drastic change or wishing for a new change in your life. She wants to make drastic changes in her life, to better herself and to become someone dependable and capable. Whether you all agree with her or not, I wouldn't say it's the worst choice to make, but she could have definitely been more clear with her intentions.