Selmar is an employee, not a friend. Would that make a difference?
I think Selmar fell head over heels for Stephanie, but was "punching above his weight ", as we say in the UK. When he realised she wasn't interested and started her friendship with a younger man disillusion set in. You could see the anger and pain in his face during the blogs when Philip first arrived. Selmar was so jealous of the younger man. He couldn't believe it. He started going away at this point.
He's stayed at the chateau because it's an easy parkup for his van, he gets meals, alcohol, parties, in exchange for some work. (He's no longer doing much work). He's an old hippy looking for somewhere good to crash and has fallen on his feet. He needs to be moved on. I suspect Stephanie is too afraid to confront him directly. Matt and Dan tried to deal with it in a crude way, with the rough bantering about where his van should go. I think Selmar has some difficulties as he didn't take the hint. He needs to be moved on now. I'm not Steph fending, but I would want him out too. I've lived in communal settings and I've seen these "very sweet, good with animals, spiritual guru" types, who don't contribute much to the community but just hang around, taking not giving. I would applaud Stephanie if she just told him to leave. Her sort of setup will attract hangers on. Sorry, I think Selmar is good at heart, but he needs to go. He's done well out of the chateau, free lodgings for little work, got his face on YouTube, got his own vlogs, got a new girlfriend. Just go now Selmar, while you've still got dignity and good luck to you and Tatty.