The desire for a family, to have a special someone to romantically love, the desire to have babies/children are all a good. The object for/the direction in which these desires are directed towards the fulfilling of these is where the issue of disorder lies. When these are directed to a person of the opposite sex, that is how God ordered things - until through Adam and Eves fall, the concupiscence to sin entered mankind, which is when all disordered desires, attachments entered.
Acting upon any disordered sexual attractions - same sex, adultery, pedophilia, bestiality is when the person sins and is culpable for the actions whether it be in thought, word, deed. Consent to these thoughts, words, deeds are sinful and the person is culpable.
We all have to fight against immoral desires, to turn our thoughts away, to not act upon them.
Think of a lady who was abandoned by her husband. She is on her own. She still has sexual urges, the desire to be love by someone and to share her life with another. But until her spouse dies, she is to live chastely and do her best to not consent to sinful thoughts or acts either with herself or with others. So in this example, if this was to occur when the lady was in her late 20s or early 30s, and assuming both she and her husband lived until their 80s, then she would be on her own for 50 years or so. It is a sacrifice she can offer to the Lord. It’s not what she wants, but it is what is morally just in Gods’ eyes.