I have often heard it said that it is better for more than one person to be involved in a startup. There is merit to this logic because the lows can be particularly low and if nothing else having another person to share them with is helpful.
This situation is more pronounced when you are in a software development environment where you really need to have another person to brainstorm and bounce ideas around with. Another point to consider is that if you are not in a place of work and there are no colleagues around you are also missing out on the subtle social interactions which help to make your work productive.
I have devised ways to cope with this situation, as I am currently working on my startup alone. Firstly I am grateful to people whom I can talk to and share the burden, writing a blog also helps. There are also co-working environments which help with the social interactions identified above, although I have not yet come across such an environment in Austria. Engaging with other founders that are going through this same process also helps.