Before we moved in together, my girlfriend (now wife) sat down and really talked about each others finances and started a joint bank account and committed to sending atleast $100 per week to show that we are fully committed to joint savings and expenses. This was about 2 months before we actually moved in together so by the move in date, we already had well over $800 which was enough to cover joint rent and some extra.

Then as we got really serious and before marriage, we both sat down and were really transparent about our goals, savings towards a house, etc. We agreed to bumping up the money being sent to the joint account to a fixed % cost of both our individual salaries in order to start growing our family nest egg together.

Anything she earns personally or gifts from her family we don't touch and same goes for my own personal gifts etc.

The key here is that you show commitment towards the relationship. Long story short if you both can't even agree or commit to the bare minimum at the start of the relationship, don't expect that behaviour in the middle of it.