Man initiates adultery because of egotism

This discussion of adultery is presented before Rosh HaShanna as a way of understanding the nature of sin and consequently how to do teshuva. Adultery is used as a metaphor for the Jewish people betraying G-d - either because of failure to submit to G-d's will or because of lust for other things. Adultery is explained differently for men and women. Women seduce a man primarily because of sexual or emotional needs. This is described in great detail in Mishlei (5:1–19), Mishlei(6:24–35) , and Mishlei(7:5–27).  

This Kli Yakar explains that men in contrast, initiate an adulterous relationship from egotism - to have that which another man has exclusive rights. This is also the contemporary explanation for rape i.e., that it is an issue of power - not lust. The following is a cogent explanation of a puzzling assertion (Sanhedrin 110a), that Moshe was widely believed to have commited or was interested in committing adultery.

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Kli Yakar (Bamidbar 16:4): And Moshe heard and fell on his face – Sanhedrin (110a), “What rumor did he hear? This teaches that he was suspected of adultery as it says in Tehilim (106:15), Everyone was jealous of Moshe in the camp. That means that everyone warned his wife because of Moshe [and that is why Moshe moved his tent outside the camp].” This is very far from being indelible. We can’t learn this from Tradition because who said that this suspicion was exactly at this time - because the verse itself implies no such thing. Therefore I claim that the author of the Agada wanted to explain the verse, “That all the community were holy and therefore why are you elevating yourself above on the community of G‑d.”  He was bothered by the question of what is the relationship between “holiness” mentioned at the beginning of the verse and the “elevation” mentioned at the end. And if you want to say that there is a relationship between them and that the holiness means it is correct to stop the elevation – then Korach should have simply asked, "Why are you elevating yourself above the holy community?" Obviously Korach was speaking to Moshe in a manner similar to Sotah (4b), "Whoever is conceited will eventually commit adultery" or alternatively (Sotah 4b), "Whoever is conceited is as if he violated all prohibited sexual relations." As is known that wherever you find holiness (kedusha) you will also find protection against sexual sins because sexual sins degrade holiness. This is what Korach said from on his own recognition (sevara), "All of the community is holy and they are protected against sexual sins so therefore why are you elevating yourself and lording it over everyone? Such behavior will cause you to stumble concerning adultery and that will bring about the profaning of the holiness of the people." That is why Korach referred to "the community of G-d" at the end rather than "the holy community" since Korach thought that Moshe had unjustly elevated himself therefore there was no holiness. That is because whoever is egotistical will in the end be involved in adultery and this causes a profanation of the holiness of the people. Moshe realized that Korach suspected him of adultery and that is why the Torah says, "And Moshe clearly understood what Korach meant and that is why the Torah said, "And he fell on his face." The underlying reason for the relationship of egotism and adultery that whoever is egotistical is continually checking all types of authority that he sees others have – with the desire to ultimately have everything under his control and authority. He is relentless in his looking into all types of authority until he eventually looks into the exclusive authority that a man has over his wife. The egotistical person wants to have control of this authority also. That is why it says "that in the end" because in truth it is at the end of the process of checking authority and the final barrier for everyone. This is a very valuable explanation that fits well with the language not only in this parsha but also the language of the gemora.
 Update
Bamidbar Rabbah (9:3):.. There was an incident with a woman to whom a manmade advances. She asked him where he wanted to have their meeting. [After he told her] she went and told his wife. His wife went to that place and they had intercourse. He was very upset when he found out what had happened and prayed for death. His wife told him, “But it was your own bread that you ate from and it was from your own cup you drank.” She said that the cause of his trouble was that he thought that he was better than other men. The solution was to view himself as the equal of other men.