Is this possible with my ETA

hello, I visited UK last year around early November to see my best friend since we are long distance and i was there for 5 months with my eta, They did ask me questions and was pretty suspicious asking “what if me and my best friend got into an argument, what would you do?” since she had a spare room in her apartment and we were planning for me to stay there, after multiple phone calls with my best friend, they allowed me in.

I want to surprise my bestfriend by visiting her on her birthday (October), do you think they will let me in? I plan on showing them that i have a return flight and everything, Im just preparing myself and seeing what is the best idea for this situation.