The Talmud compares the first and second Temples, noting that many more High Priests served in the second. Towards the end of the second Temple era, many rich men bribed the secular authorities to get the position. Since they were not righteous they died within the year, during the Yom Kippur service. The Talmud brings the spiritual reasons why both temples were destroyed, and on the theme discusses the Tabernacle at Shiloh.
Shiloh was the original location of the Tabernacle, the portable sanctuary used in the wilderness, when the Jews first resettled Israel. The Bible does not record that it was actually destroyed, but that the Ark of the Covenant was captured in battle, which ended the ritual offerings there.

Rabbi Yoḥanan ben Torta said: Due to what reason was the Tabernacle in Shiloh destroyed? Due to two problems: Forbidden sexual relations and disrespect of consecrated items. Forbidden sexual relations, as it is written: “Now Eli was very old and he heard what his sons were doing to all of Israel, how they lay with the women who did service at the opening of the Tent of Meeting” (I Samuel 2:22).
Even though Rabbi Shmuel bar Naḥmani said that Rabbi Yoḥanan taught: Anyone who says that the sons of Eli sinned by engaging in forbidden sexual relations is simply mistaken, even according to his interpretation of the verse that it was due to the fact that they delayed the sacrifice of their bird-offerings by women after childbirth; this was so serious that the verse blames them as if they lay with the women.

As background, married women came to the Tabernacle to sacrifice doves or pigeons as offerings to complete the purification process after childbirth or zivah, in the latter case they needed the offerings to be brought before engaging in sexual relations with their husbands.
Eli’s sons delayed the sacrifice of these offerings, and thereby delayed the return of these women to their husbands. Even though, per Rabbi Yohanon, Eli’s sons did not actually have sexual relations with these women, the verse teaches that what they was considered equivalent in evil. The Netziv writes that it can’t be that the Tabernacle would be endangered for the sins of two men, rather their behavior reflected a prevalent attitude that the intimate relationship of man and wife was not of primary importance.
We have discussed that in conventional Jewish wisdom, interference with someone’s intimate life is anathema. In this case the priests were preventing married women from going home to their husbands the same day they arrived, and delaying their resuming this key component of their relationship after an interruption. Preventing a couple from sleeping together is a tremendous sin.
We can extrapolate (without condoning) that in modern times it is also vile to interfere with a man trying to form an intimate relationship with a woman. What they do is their own private business, not that of others.
Some men can be motivated, through jealousy or by trying to ingratiate themselves with women, to be a “white knight”, a man who tries to protect women from the advances other men. Modern women don’t need your protection and are not grateful for it. However, interfering with someone else’s intimacy is considered as bad as sleeping with a married woman.
The second reason – disrespect for sacrifices – is another piece to the puzzle. The sons of Eli demanded meat from pilgrims, even before they had completed burning those parts of the animals that must be offered before people can partake in the meat. They wanted immediate gastronomic satisfaction for themselves, even before finishing the Divine command and helping other men gain atonement.
These two reasons are two sides of a coin. These priests were fine with making women wait before going home (and to bed) with their husbands. But they were unwilling to wait to finish the offerings properly before getting their own portion of the meat.
Beware of people who make you wait for what you need, while insisting on getting what they want right away. This behavior is a strong indication of arrogance and narcissism.