I don't see why it can't be done as it is a certain genre of sorts. Hell, people watch the bachelor and bachelorette on a regular basis just to see who the final couple may end up being, so creating an RP around this premise isn't too far out of the norm.

A few things need to be addressed though and that's with the characters, and the interactions. You need a well designed male character, not some boring schmuck. They need to be desirable, attractive, either walled off person who never asked for this or an open charmer who knows the females will fall over for him (depending on the type of harem story you want), and most of all interesting for the players (both male and female) to read. If it's none of these then how can you expect characters to generate a lust/love for them without it sounding like some trashy love triangle.

You also need to avoid, like really avoid, inserting yourself into the character as a Mary Sues/Gary Stus. If you're creating this to get your rocks off on an online roleplay where people desire over an avatar of [i]you[/i], stop immediately... what you are doing is not fair on the other players who are probably in it to create a unique story experience. There are plenty of places out there for you to cyber your kinky fantasies, and the Guild ain't one of them. I can't speak for all 1x1s however, but this is a group we are talking about; different people with different threshold levels. Make it clear what it is you want and perhaps you'll actually make this happen.

Lastly, determine the type of RP setup you want—public or private. PM RPs can cater to 5 people. That's 4 female characters and 1 male if it's 1 per player. Private RPs do open to more adult content but run the risk of people feeling more uncomfortable about the direction. A public Roleplay will have certain restrictions on what can be written, but at least the players will feel comfortable knowing that what is posted follows some decency.