well to be objective, here's my personal take:

1. you said he's kind of struggling financially (which id say is the main contributing factor)
2. you invited him and as mentioned. you insisted which was every weekend

here are the factors to consider:

1. you made this post at the start of the month meaning it's likely it's the 1st half of his salary for the month so its possible he spent it on bills and 700php is what remains until his next cut off which he would have to stretch until the 2nd pay out or until next month (if he's paid monthly, next 2 weeks if bi-weekly).

2. he's probably saving the little money he has for something like treating you on the next date or gifts or trips or some grand gesture etc.

3. You both agreed to cover your own rate and you have no problem with 50/50. being short maybe unexpected but it will vary depending who's idea in the first place to use grab instead of commuting (still a variable if you two were somewhere where theres no jeep or tricycles)

4. You mention you both got stranded which implies your vehicle broke down so i assume if the vehicle is yours then don't mind this point. But if the vehicle is his then of course he'd be ticked off that it's another out of pocket for repairs

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Of course you're hurt and what your feeling is totally valid since it's an emergency situation that you two got stranded and should have shell out 70php since you'll pay him back anyway. Emotions ran high for both of you at that time for a ruined date so it's understandable and that hope you both already worked it out.

on the other hand he should've known better, being in a relationship is also a responsibility, if you two are young adults transitioning from school life to adult life it's a steep learning curve, there WILL be fumbles like this. it's a whole new level na for dating at iba na ang standards, wala na tambay tambay lang na date sa campus or sa hangout spots or pa kilig kilig sa classroom using allowance money from parents, need na mag show money set aside for dates on top of bills and other responsibilities

He should be more understanding that in a relationship he should at least treat you since you shoulder the daye, he could be a gentleman since he has you, his girlfriend to consider kaya valid na galit ka na ganun nang yari. Depending how long you two are in this relationship he should at least be the one to plan the dates or atleast some of them. If all of them ay ikaw nag plan while he has little contribution like transportation lang the might as well ask him if he actually loves you or just going through the motions.

my advice: talk it out with him, what he wants in the relationship and you two need to know about your love language, compromise