If your birthday is days apart from your spouse/girlfriend/boyfriend then you guys will have similar transits. Having similar transits means you could be going through the same thing.
Joe and Teresa Giudice are a perfect example. Joe was born May 22, 1972 and Teresa was born May 18, 1972. At the time they were born the alignment of the planets was close to exact.
They have just been convicted of fraud and sentenced to jail. So what happened?? Since their charts are similar, they both experienced Neptune in Pisces square Saturn in Gemini. Neptune is the ruler of jail and Saturn rules authority/law. On top of that they are both in their Uranian opposition which is when Uranus shakes our *sses up! Also known as a mid life crisis.
So, if your mate has the same birthday or close to it and he/she is doing something crazy stay out of it because you could be dragged in it as well.