You are going to have to persevere.
A LL will want to charge you as much as they can to account for he extra utility.
Unless you know the other tenants then they tend to be against couples, sex, bills and gets in the way of general house harmony.
Try spareroom to get an idea of the market and have a look there am sure its possible. obviously the better solution is a studio and then you can really live like a couple.