I was refused because we entered together last time, I had a bad gut feeling and that feeling was right :/
That's bad advice
Why would you be refused for entering together? Friends, couples and spouses of different nationalities enter the UK together every day and have no issues.
You were refused because the immigration officer believed you were not a genuine tourist and were an overstay risk because had already been in the UK for almost 6 months and without a return ticket they were worried that you wouldn't leave.
As you said in your other post you were also under the influence and didn't stay calm, which likely would not have helped your case and may have contributed to their decision to refuse you entry.
The first red flag would have been your lack of a return ticket - without a return ticket, it's pretty likely you will be refused entry. Did you also have proof of a job, a home and a life to return to in your country of residence? What about funds to support yourself for your trip?
These are all things you need to be able to show, and without them, you can be refused. There is nothing in the immigration rules that says you can be refused for entering with your UK citizen boyfriend or girlfriend.