I've failed more times than I can count in my life. Some failures are somewhat benign - failure to read my scriptures, to reach out and do good for others, or to work out every day. Other failures have a much bigger impact - failure to stay out of precarious situations, or to resist temptations or get out when the situation goes bad.
Failing is painful. And when I fail, Satan tries to convince me that I'll never make it. It's not worth the effort. I'll never be good enough. I've sinned so much that God could never forgive me. And even if He does, I'll never be happy anyway. The lies swirl around me and I find myself with two options - get up and start over, or stay in the gutter and be brainwashed into changing my dreams.
For me, the vision is being married, with a family. When I realize that I've dated yet another girl and I'm not at all attracted to her, and then I find myself dreaming about a guy in my ward, I have the same two options. I can keep moving forward, believing that God will bless me no matter what happens, or I can lower my vision and give up on the ideal. Thankfully, I've always had the strength to get up and start over. To pick up my shattered dreams, put the pieces back into place, and ask God for help.
For guys who are attracted to guys, attraction can be a constant issue. But attraction isn't the same as sin. I make mistakes and repent just like everyone else. If I make big mistakes, yeah, the repentance process takes more time and effort. Sometimes a lot of time. And a lot of effort. But it's still available. It is worth it, I can do it, and the Lord will help me to be happy, fulfilled, and ultimately receive my righteous desires. The danger is in giving up and stopping my progression - believing that following temptation will make me happier than following God. My prayer is that I will always have the faith to keep going.