What other person? I'm assuming here you are talking relationship involving sexual relations. The normal, the default, is no sex, followed closely for "normal" by marriage. Who are you talking about making happy? Satisfaction of the partner is more to the point, in marriage, though to be honest, I think continual affection and deference shown does more for the other person than a sexual climax. Outside of marriage, sexual relations is wrong, period.
To fail in either respect is not in itself a sin. The reason you fail may well be.
I keep hearing questions like this, that to my mind show a lopsided worldview, where sins are focused on, instead of God. Sin, in my opinion, is much more urgent to deal with than to get hung up on sins. What is in the heart controls what the body does.