If you want someone, you have to be willing to wait for them and trust that what you have is real and strong enough for them to wait for you. If somebody jumps ship for you, that fact will always haunt you because you'll know they're light on their feet. Spare yourself the paranoia and the pain and walk away until the coast is clear.
To those out of work, it may seem unfair for someone to complain that they aren't happy with the type of work they are doing, but the more we like our jobs, the better we do them. In the long run, this doesn't just make us happy - it makes businesses more successful and increases employment even further.