Whether you are married or not, falling in love with a married man (or woman for that matter) is simply a bad idea, and yet it happens time and time again. Of course, you can't help who you fall in love with; it may be something that through circumstances and time you have found just happened.
You now have a real predicament on your hands and a certain amount of personal pain to endure whichever direction you choose in this matter. If you are already in a relationship yourself, then you perhaps owe it to your partner to forget about this other individual. If falling for someone else has highlighted a problem with your own relationship, your time would be better spent trying to sort that out instead.
If you are not currently in a relationship, then falling for someone who is married can only go one of three ways
1. You will date each other for a while and after the excitement of the fact that this is an affair and the added element that you are doing something naughty has worn off, it will come to a natural end. If you are in relationships, this will only happen if you never get found out!
2. One of you will fall in love and want to take it to the next stage, but the other will never leave their partner - but may promise too. Quite often, people find that affairs make their own sex life more interesting.
3. You will find that you are both in the wrong relationship at the moment and separate from your existing partners and start a real relationship together.
Of course, in any early stages of a relationship the feelings are really strong and the sex is exciting. However, splitting a couple up and having an affair could be a painful experience and probably not just for you. Don’t forget that the person you have fallen for already has a spouse - perhaps kids at home too and then you have a whole new element to think about.
If the guy doesn’t know that you have a thing for him, it’s probably best to leave it that way. Try to focus on your own relationships and the things that are happening in your own life. There is no doubting the impact an affair of this nature would have on your own state of mind.
Think seriously, about the effects this could have on everyone involved, and ask yourself, Would this just be for a bit of fun? Or can you imagine every day and night with this person, holidays, good times, bad times...awful times? The course of true love never runs smooth and sometimes people just want what they cant have. Consider all of this, then pause, consider your future, and theirs and go with what feels right, just remember that some things can't be undone if you regret it.