It was a very serious mistake to move Lexy & Pete to Em & Sid's apartment.
It is not easy for two couples of strangers to share the kitchen, the bathroom, the toilet and the living room and this can create bad moods and/or tensions that do not facilitate everyday life and it is not even certain that they favor sex in common.
Not all couples practice threesome and foursome but they still offered high quality sex. Think, for example, of Alice & Pavel, Jeff & Violette, Lily & Noah, etc.
Forcing 2 couples to live together does not mean that they, automatically, have to have sex together. This may seem (at least for now) the case of Stella & Stephan with Evi & Alan.
A couple who lives alone in a flat can have sex in complete freedom where, how and when they want. But the presence of other people at home could inhibit this possibility. Just think of a couple who are watching TV that they want to have sex with; if there were 2 other people present, maybe it would not be possible.
If this couple chooses to practice sex with other people, it is free to do so by organizing meetings, parties, dinners, etc.
This is the case, for example, of Lola & Otto, Mira & Henry, Cleo & Axel, Clara & Stas, Edda & Joe, etc. They are on their own, they make us have fun and, when they want, they can have sex with other people.
I remember only one case of 2 cohabiting couples who lived in harmony and had sex of all kinds alone or in company. These were A&A and B&D that were true "animals" of sex.
To conclude, I think the best solution would have been the following:
1. Move E & S to a smaller apartment and offer them the last chance to return to a normal life without quarrels and tears but with a more intense social life and acceptable sexual activity. Otherwise they will have to leave the VHTV program.
2. Leave L & P where they were and maybe add a new couple there (they had a guest room). If Alex really wanted to move them he had to leave them alone (as mentioned above) and they would have thought of making the house profitable by inviting people and organizing parties.
Obviously this is only my opinion.