I've been watching RLC for over 3 years now.. I noticed some couples are really in love and sharing good feelings, some others broke up and left the project and this is well understood..
But there's another type of relations which I call "living there for money and free lodging".. Dasha and Demid are a good example for that.. We never see them kissing, embracing or cuddling.. Their sexual relation is very cold and we don't feel that affection we could see between Adrian & Daniel.. Another examples are Zoya & Lev, Leora & Paul..
That's why I think some couples are staying with each other for the sake of money and lodging and not to be alone..