When I used to believe in love, there was a time in which I lived with a girl in my apartment for almost 2 years.
The experience was awesome. Not only sex but friendship everyday, help each other, try new things together, etc.
Then, the routine showed up and ruined everything! We got fed up with each other and broke up.
Now, I'm a single NEET and I doubt I can believe in love again.
If it's with someone you love it's amazing at the start. But if you spend too much time together in the same house then it can easily lead to petty arguments and bickering. So I used to enjoy it but you realise that personal space and 'me-time' is a blessing. You need that balance when living with a partner.