In Jason Evert's new book, "Theology of his body / theology of her body" he tackles a tough question- perhaps one that you struggled with.
A young man asks him "I know it's wrong to sleep with some girl you don't care about, but what if you really love her? You see, the girl I'm with now, I'd die for her. I'm serious. If someone put a gun to her head, I'd tell them to shoot me instead. That's how much I love this girl."
That's great. Really, it is - it is great to see that you would lay down your life in effort to save the girl you love. So do it. But unless your girlfriend has some secret past in the mafia, there is a pretty good chance this is never going to happen.
But what if your boyfriend/girlfriend died today? When he/she went and stood before God, would they be able to talk to Him about you and say that you always put his/her soul's health before your own physical pleasure?
If you are ready to die for her, then it's time to put your lust to death and guard her heart and her soul, instead of imaging what it would be like to give up your life for her in an imaginary situation.
If you are in a relationship, you both are in a situation where you have an incredible opportunity to help another person to Heaven. Don't do things that will hinder you both from getting there. Real love is shown by how much you sacrifice for each other - not how much you take from the other person to make yourself happy.
We are called to love like Christ loves the Church. Christ shows the extent of His love for the Church when His arms are stretched across the cross. How far are you willing to go for the one you love?
God bless you all (and continued encouragement for your Lenten journey!)