THe wider the orb the later the problem tends to show up in a relationship. 6 degrees is still pretty close for the planets mars and Saturn though. Mars is a planet that tends to show itself quickly anyway because it's rather aggressive in nature.I also HATE Saturn square Mars in a synastry. I think it's awful. Saturn squares can be very difficult in general, but Saturn square mars and Saturn square moon are the worst for the non-saturn native. I refuse to even start a relationship with anyone whos Saturn does this to my moon or mars.
Don't know your chart, but probably all you have to do is have relationships with people who are a year or two younger or older than you instead to avoid this in synastry.
Saturn shows loyalty and having it square your planets in your natal can sometimes indicate a hard time finding friends, coworkers or love interests who have your back.