That's strange, I thought they fixed it so married/engaged sims etc don't get random romantic relationships? My sims don't get them anymore.
The only thing I suffer on my rotations is relationship losses, depending on how long I've been away from a household (usually a long time, as I rotate around a lot of households). It is the one big thing I find really annoying, having to get to know other sims again who were once friends.
One tip: if you have Get Together, make use of the club system so that sims in the same club will stay in each others relationship panel.