Ah gee Maria - that's a tough one. One of the favorite lines in one of my favorite movies states: Don't shit where you eat. This is always good advice LOL. Yet - I have a vey close friend that married one of his co-workers (after being warned away from her by the powers that be) and they now have 2 kids over 21.
Obviously the question of favoritism comes up with all the ugliness involved. Another consideration is that you may THINK that nobody else knows - but you can be sure that someone does - and will talk about it eventually (to the wrong people too). I became an unwitting participant in a 60 year olds affair with a 20 year old office assistant back in the seventies simply because I was in the wrong place at the wrong time through no fault of my own. I saw them meeting about 5 blocks away from the office - and climbing all over each other because they thought they were safe there. As predicted it turned ugly after about 18 months (not because I said anything either). Both of them wound up leaving the company.
So I guess that my advice would be make sure that this is something important enough to you to realize the risks that you are taking. I know that you love your job and would not want to lose it. Personally - I don't see at as such a big deal. There have always been offices - and when both genders work together - there will always be sex. This is actually a good thing in my opinion - pleasure should come into your life from some direction.
So if you are going to continue with this person - have fun
