Combine a mild dose of self delusion with a huge potential payoff and world view that everything is crap and there's evil everywhere and you'll have no trouble living with yourself no matter what you do.

Is pure romantic love devoid of transactions? Many couples involve two people giving commitment and expecting commitment back. Sure, not all couples are so monogamous, but many if not most are. People have expectations of what to receive from a relationship and when they don't, they consider ending the relationship. Point out a one sided romantic relationship people will tell you to find someone better for you. Sure, it is never put in the language of 'do x, get y'.

Many social groups who help each other with resources without keeping tabs still can recognize when someone is leaching off the group, especially when they recognize the person has the ability to contribute to the group but chooses not to. People who support someone without expecting them to be paid back often have an expectation of the relationship being two sided with sentiments such as "I know if the roles were reversed, you would do the same for me." In cases where the roles do reverse but they don't do the same, you see people quite broken. It wasn't ever a strict tally, but it does hurt the person that their relationship wasn't as too sided as they expected.

We even describe people as being enablers when they give to someone without receiving back what we think is due (with that last part being defined in highly situations terms).

Romantic love is definitely transactional, just like everything else. We are animals in a physical world, after all. Anyone who says that they love someone truly without conditions just hasn't had enough of their conditions broken to know that they have them. I say this as a happily married person going on fifteen years. Our marriage is romantic, sure, but it's also a deal, and you're both putting stuff into the deal and getting stuff out of it to make it work. The romance wouldn't work without the rest of it.