So I think there are two equally good ways to split finances.

1. Based on income: The person who makes more pays for more (rent, utilities) based on a percentage of their income, and then you decide on how you split other expense like vacations and dates. It isn't practical to split a dinner bill 60/40 or whatever, so you figure out a system of expectations for dates, and then of course each vacation can be discussed as it comes up. I think based on income is the better option when two people are married or really solid in their relationship, because then it truly is a joint partnership.
2. 50/50 but the budget is based on the lower earner: You split your expenses equally, but where you live and the other living expenses are based on you, as the lower earner. For example, if I can afford $1000 in rent and my partner can only afford $500, we find a place that fits his lower budget. That way it isn't just an equal split, but fair to the lower earner. I think this is better for couples who aren't ready for "life together" but just starting out living together, or where there is a big disparity on the value of money (one is a saver, one is a spender).

And then either way, you shouldn't be going in to debt for dates, gifts, and vacations. When a weekend trip comes up, it is fine to say "I can't afford that." I pay for most of the vacations with my partner, because he is on a limited income. I want to go on vacation, and I want him there with me, so I have no problem paying. It is totally fine to tell your partner when you can't afford something- a fancy restaurant, a weekend trip- and then they can decide if they want to pay or to pick a more economical activity. If you just say "i can't afford that" then you aren't expecting them to pay, which of course you shouldn't, you are just being honest about your finances.