You just walked into your favorite restaurant for lunch. You love the food but right now you have something else on your mind. You are expecting someone else to join you and here they are. Both of you greet each other warmly. From the first time you met on the job, there has been some intense attraction between the two of you. You want to build on the emotions you are feeling and so does the other person; sort of. Why sort of? For the simple reason, they are already involved in a relationship with someone other than you.
1. What if it was you?
It seems when people get involved in these situations they never stop to think what if the shoe was on the other foot. Let's say you are successful in breaking up their relationship and having the other person all to yourself. Fine but now they meet someone else who attracts them even more than you do. What then? You wind up in the same position as the first person. Karma can be quite nasty so if you do not want to be on the receiving end than it is best to let it go.
2. Trust
The other person tells you they are engaged or seriously involved with someone else. So what are they doing there sitting next to you putting out feelers? Curb your emotions for a minute and think. Can you really trust someone who says they are in a committed relationship but is out looking for some action?
3. Wait
You both agree to pursue this further except that the other person cannot quite end their other relationship now. You give them the cornball line that, "you are willing to wait as long as it takes." The reality is nobody has that kind of time. Sure the two of you may get closer and more intimate but you are still the third wheel. As long as the other person remains in their relationship, you are sharing them. No matter how you feel now, this can get old very quickly.
4. The Explosion
It's bad enough sneaking around but now it gets back to the other person. No they are not going to do the "proper" thing and bow out gracefully. In fact they are ready to fight so as to keep the other person in the relationship but more importantly not to be made a fool of. Hurt pride is a powerful motivator. Are you willing to escalate the situation? Besides you really do not know what side of the fence the object of your affection will choose to stand on. You may wind up winning the battle and losing the war in a big way.
It is in your best interest to avoid getting involved with someone who is already in a committed relationship. There are plenty of people within your world who are unattached and looking to see if they can generate some chemistry with you. Maybe yes, maybe no. But involving yourself with someone who is already involved can take a major toll on everyone concerned especially you. The victory in most instances is not worth the price.