I fucking love to help when my boyfriend needs something, even if it's something silly if I know it will make him happy or will make his life easier I enjoy doing it. I thought that was the best part of being in a LTR, to have someone on your "team" so you can both tack problems together and therefore have it over all easier.

Don't assume people see things, especially favours, the same way you see them.

Well yeah obviously not with strangers but if i am in a relationship with someone it is ok to assume I know them well enough to know make an educated guess. Generally I part from the assumption that I am not dating an asshole because I am not an asshole myself, but if I learn any new information that challenges that knowledge it is ok to act accordingly as OP just did.

It makes no financial sense to look into rentals when your partner has an available car you can ask to use first, and a rental charges you a "contingency fee" because they don't know you and don't know what you could do to their car. You're supposed to trust your parter enough to have sex with them, running the risk of creating a human every time. If you cannot trust them with your car then you're making a very dumb decision by trusting them with your sperm or eggs and you're just brewing a potential life of sorrows.

Expectations hurt only the person who has them.

That's a very broad statement, like yeah ok, all suffering comes from desire so lets all stop wanting things and become buddhists. The fact is that you're not being unrealistic expecting a quality partner if you're a quality person yourself. You will be disappointed and have to deal with selfish or stingy people but the smartest thing to do is to keep looking, not to become selfish and stingy yourself. Your view of relationships is not just cold from an emotional point of view but it is not even frugal, moreover a person with these attitudes would be seen as an extremely unattractive partner therefore limiting their choice further.