Yes its the statements 888,
I know i need o write a statement about our relationship, but is there certain topics that need to be mentioned. or do i just write everything that comes to mind since we met until today?
If you haven't done so already, I would suggest looking through the partner migration handbook.
You will find a lot of answers to questions in there.
You and your partner will need to write statements on the history and development of your relationship. In your own words, separate statements detailing things like how you met, when you committed to a shared life together, when you became de facto/engaged/married. More information can be found in the partner migration handbook I linked above.
There are four categories of evidence you will need to provide in your application for a partner visa. They are:
• Financial aspects - joint bank accounts, shared leases, car insurance, loans, credit cards etc.
• The nature of the household - how your household is run, who does what for household duties, bill payments etc.
• Social context of the relationship - evidence of you and your partners social life - pictures on vacation, with friends, family, concerts, invitations etc.
• The nature of your commitment to each other. - proof that you and your partner have a shared commitment to one another. Showing each other as the others emergency contact, wills with each other as the executor/beneficiary, shared medical/dental benefits.
Those are just some suggestions of evidence you could use to satisfy those four categories. Obviously everyone is different and individual circumstances change. To give you an idea, this is how we broke ours down.
• financial aspects - we broke ours down into two sections, household bills and joint purchases. We included a brief statement for both and a table of contents outlining what was in each section. Then in each section we included screenshots and other evidence that we listed in our table of contents.
• the nature of the household - In this we included a brief statement on how are house was run, who paid what, who cleaned what and pictures from around our house showing that we both live there. \
• social context of the relationship - this section we broke down into four
sections. We did this to reduce the size of the file and to give a look into each aspect of our social life. In each section we included a brief statement as well as a table of contents describing and showing what evidence we included. Our four sections of social aspects were joint travel, social events with family, social events with friends and joint memberships we held.
• the nature of your commitment to each other - in this section we included a brief statement as well as a table of contents outlining the evidence we provided. Everything from work emergency contact information, the wallet size cards of emergency contact we each kept, our wills, medical and beneficiary information as well as cards we've given to each other on anniversaries, birthday's etc.
Like I said, each application is different, it's best to go through what you think you have and sort it accordingly.