Ah, isn't it wonderful being on the horns of a dliemma.
I think you actually answered your own problem by saying this has gone on for three years. You don't sound particularly happy about this.
It sounds like you're on a rollercoaster, from high highs to low lows. I don't think that anyone likes that except every once in awhile. Most of us prefer something fairly constant, and I'll bet you're the same.
So, how to get off the rollercoaster...
Just get off! It's your rollercoaster--it's your life. Yeah, yeah, easy to say when it's not your problem.
It sounds like you may need to just make a break. A person doesn't have to be jerk to break things off; if you're in any kind of friendship that isn't making you happy then you need to make the break and move on.
This "maybe one day we'll be together" may be true and if you're willing to wait for something that may never happen then have at it. People (women can use it, too) can use that line when they want to be a puppetmaster/mistress. to someone willing to buy into that scenario. Are you willing to take a chance on waking up 10 years from now, or even five years from now in a relationship that hasn't moved forward and you may have let chances for other relationships pass you by?
And you say this guy's a client?!

Major red flag here, unless he's no longer doing business with your company. If he's still a client and something goes wrong you could be in for a demotion or firing. Businesses don't take things like that lightly. Do you live in the shadows and have to keep this relationship a secret? If so, another red flag.
It's OK to run the gamut of emotions as to why you find him so attractive. I've been there plenty of times myself. The answer changes from hour-to-hour or more frequently or can be situational. Have you considered keeping a diary and just pouring your feelings out on paper? Just write and write and write, regardless how how irrational you may believe you're feeling. Just letting go of all the confusion may help to cut through some of the mist on your path.
Do you sit alone nights waiting fo him to call or to come on-line? I did my share of the former during my single life (I got married at 38, pre-internet). It's easy to look back and say "what a waste of time" because I had to go through it, as will you.
But you can decide how long you want this to go on and what path you want to take. You have that power and you can do whatever you want with it. I've posted replies (as have others) to several people who have posted in this forum and the answers are pretty much the same:
1. Nothing happens overnight. That is extremely frustrating when one is unhappy and wants the unhappiness to go away.
2. Consider finding other ways to spend your time. Take up a new hobby, join a new organization, just get out and meet new people. Even if you have to force yourself to go to the mall and window shop, at least you're with other people and away from the phone.
3. I keep forgetting this is the age of cell phones. Unless you really need the phone on, turn it off. Yes, you'll be tempted every few seconds to see if he called or texted you but if you make that first step away, the times between the checking for the texts or messages will get longer and longer.
4. Consider what kind of a relationship you want with this guy. I mean, seriously consider. In one way, you're waaaay smarter than I was. I fell for a guy I met on vacation and within a few months I moved 1000 miles away from where I grew up to be with him. I went into it with eyes wide open (I was in my late 20s, old enough I thought to know better

) and the glitter wore off not long after I got there (I think it had started to wear off before I got down there and I didn't realize it). The rfact that you're not moving to be nearer to him is smart, smart, smart and I applaud you highly. In my case, life handed me lemons and I was able to make lemonade in spades but the lemonade didn't come cheap.
I'm so sorry you're in such turmoil and you've prolly cried yourself to sleep over this for awhile. Do you have someone you trust that you can talk about this to, or do you have any kind of support system? I've been lucky that way; there's always been someone around when I've wanted to talk about a problem.
Of course, you can always post here. Sometimes it's easier to use anonymity (sp?) in starting on a path to wellness.
If I was you I'd skip the conquest thing. Be careful what you wish for, you may get it. If you want to "win" him you want to get him "legally"--no game-playing, no invegling, no using "wiles". How would you feel if he tricked you into a relationship? I can't think of any relationships I've had or known of where trickery worked. Playing a little "hard-to-get" is fine, but out-and-out chicanery is beyond contempt.
Go on with your life, but go your own way. You sound like you have a good head on your shoulders all in all, so decide what is best for *you* in your heart of hearts and go after it. You'll change your mind along the way, that's what life's about--makes you a more well-rounded person. You may even make the same mistake a few times. God knows I have!

But that's how one learns (and sometimes the lessons can be hard to learn).
Take your time, cry when you need to, keep posting and good luck.
Vitrual hugs from my part of the country.
P.S. Sex is one of the worst ways to try and keep a relationship going. You'll be very sorry in the end.