[mreome]

Social interaction and co-habitation is not a zero-sum game. I'm sure we're both working from our own personal experience here, but for me I've always found living with a room-mate or significant other to be a net positive for both parties. It's easier to cook healthy home meals for two then one, both in terms of purchasing/portioning and the ability to split up or alternate the work. It's easier to not skip workouts or social events when you hold each other accountable for them. The mental and emotional stimulation that comes from having someone else to talk to and do things with rather than passively consuming mass media alone.

Sure, it's possible for someone with bad personal habits to be a negative influence on someone who struggles to maintain their own good habits, but two people with generally good habits can easily create positive feedback that allows them both to improve.