Sexual intercourse is reserved by nature for a lifelong, exclusive, male/female relationship for the begetting and raising of children, and the mutual care of the spouses. This is intuitively obvious and proven by common experience. Therefore, those who reserve intercourse for marriage are happier than those who don't; just as those who eat as nature intends (in moderation, primarily for nutrition and growth) are happier than those who abuse food (who overeat, eating primarily for pleasure).
Nonsense.
This is intuitively obvious and proven by common experience
Translation: This is Aquinasfan's opinion, nothing more.
Therefore, those who reserve intercourse for marriage are happier than those who don't
You have no evidence to support this speculation.
"Sexual intercourse is reserved by nature for a lifelong, exclusive, male/female relationship for the begetting and raising of children, and the mutual care of the spouses. This is intuitively obvious and proven by common experience. Therefore, those who reserve intercourse for marriage are happier than those who don't..."
This would be true if everyone's nature were the same. We're not all the same though. We all react differently to the various events, sights, and sounds that occur around us. Closer to the subject of this thread, we all react differently when we become sexually aroused. I don't think nature intended us all to react the same way, or live our lives the same way. I think saying that those who reserve intercourse for marriage are happier is a very broad assumption on your part. It's a tough thing to gauge. At some point you have to ask, "Did you save yourself for marriage"? (not a question I ask people I meet). Then, you have to evaluate their happiness based on what you see, which in most cases is only what they want you to see.
Sexual intercourse is reserved by nature for a lifelong, exclusive, male/female relationship for the begetting and raising of children, and the mutual care of the spouses. This is intuitively obvious and proven by common experience. Therefore, those who reserve intercourse for marriage are happier than those who don't; just as those who eat as nature intends (in moderation, primarily for nutrition and growth) are happier than those who abuse food (who overeat, eating primarily for pleasure).
Stating that two plus two equals five does not make it true. I reject that "nature" reserves sexual intercourse for any such situation as you aver. Were that true, either there would be no time at which pregnancy was improbable or humans would be disinterested in sexual activity at such times. Additionally, if what you aver is "reserved by nature" were indeed reserved by nature, humans would have no interest in intercourse if they were not in a monogamous, committed relationship. Again, as the predicate of your proof is under dispute, your conclusion is as well.