How to Have Your First Argument in a New Relationship and Still Remain Marriage Material

No one likes confrontation. We all wish life could be rainbows and butterflies 24/7, but no one is perfect and relationships are not going to be either.
I was sitting down with a friend, and she said, "Mike, I have been dating a guy for 3 months and he is great, but one thing is really bothering me."
"What is bothering you?" - Me
"We make plans, but he is consistently late." - Friend
Well funny enough, I am usually late so this is a problem my girlfriend constantly has to deal with. Thus, I've instructed my girlfriend how to get me to show up on time. Yes, I know that she is using my own little trick on me, and YES IT STILL WORKS!
So, last Friday my girlfriend needed me to be somewhere at 8PM on the dot: We could not be late. She called my on Friday morning and said, "Mike, you will make me the happiest woman alive if you picked me up at 7:15 on the dot so we can be on time at 8PM"
I said, "Sounds good I will be there"