Most Helpful Guy
1) Don't expect someone to change. Don't stay in a relationship that is conditional on them changing.
2) Compliment her more, a LOT more. Girls thrive on that for some reason.
3) I know it's stereotype. But when she says we need to talk, then we really do need to talk.
4) Related to #3. If it's important to her, then it should be important to you, even if you don't understand why. If she says it's important, then it's important.
Most Helpful Girl
It taught me that, love isn't always fully appreciated. That taking advantage of someone isn't always physical. Things I knew but had to experience for myself. It also taught me what my preferences are in a partner and in a relationship. The sappy feelings and appearances will vanish, and having someone who's willing to take care of you and do whatever is necessary, all while loving you the same, is priceless. Again, something obvious, but I didn't don't expect it from my relationship.