So, I have a conundrum. I have a strong calling to be a priest, and am pretty much set on the idea.
What a blessing.
For now I am still trying to figure out if I should be a religious or diocesan priest, but I have another issue.
Religious.

But I am biased…
I have a girlfriend, who knows that this is how I am going to choose, and it is making her incredibly sad. I care about her a lot, and I want this to be as painless for her as possible. We’ve been dating for about 5 months now, after being very close friends for a while. We’ve both helped each other through many problems, which has lead me to be the person in life she looks to most for help and comfort.
I broke up with a long time girlfriend about a year and a month ago. We had been dating for two and a half years.
Obviously, me leaving her is going to be a big problem. It’s made bigger because she isn’t a Catholic (she in fact dislikes my faith), which makes it hard for her to understand this. Worst of all, she is very prone to depression, and many times I have had to pull her away from attempting suicide. So separating from her is just going to create a lot of pain, and possibly drive her to hurt herself. That’s the last thing I want.
The deeper the relationship you have with her, the more hurt and pain there will be. Pain is unavoidable at this point. But if you string her out, it will be more painful.
So my question is, how do I handle this? I probably won’t be joining a seminary for at least another year, so should I separate now, or once I have actually picked where my vocation will lead me? And most of all, how do I make this hurt as little as possible? I know it will have to hurt, but I want to handle this in the kindest way possible.
Dating is essentially ordered toward marriage. If a man discerns that he is definitely not going to marry a woman, then he ought to stop dating her. I can see how you might be tempted to keep the relationship going longer, but you need to resist this. First, it’s just stringing the poor girl along for a ride.
You are sure that you want to be a priest, but she is sure that she wants to keep you. If you wait a year to break up with her… your relationship will be three times longer than it is now. Emotional bonds deepen incredibly over time. Habit increases over time with repeated actions. It will be harder, not easier, to break up with her later.
Second, you are certain that you want to consecrate your life to Jesus Christ. The time to start living in anticipation of that consecration is now. From this moment you need to start living in anticipation of the life which you intend to adopt. And that includes not dating. A crucial part of your priestly ministry will involve being in chaste, non-romantic relationships with women. The sort of close emotional and psychological intimacy which a dating relationship has-- and which leads into the close emotional and psychological intimacy of marriage-- is something that you need to wean yourself off of. You need to start forming the sorts of relationships which a celibate male should form. That includes women, of course, but in a different way than dating.
I don’t mean to be harsh here, but you can’t date two girls at once. Being open to discerning is one thing, and discerning is another. You are full-fledged discerning. You cannot date a girl and the Church at once. It’s dishonest to both of them. Your heart is moving in two directions.
As to breaking up. It will be hard. Incredibly hard. Perhaps the hardest words that you’ve had to say in your life. I know, on my part, that breaking up with my girlfriend was incredibly hard. It will be a cross. But the Lord wants to break you so that you can be his faithful minister. You will feel pain and loss when you break up with this girl. The Lord wants you to know this pain, just as He knew pain in this life, so that you can be merciful to His Church as a shepherd of souls. Remember that the Epistle to the Hebrews said that Jesus
…***had to be made like his brethren in every respect, so that he might become a merciful and faithful high priest in the service of God ***(Heb 2:17).
The Lord too wants you to be like your brothers in every way so that you can be His faithful priest. You have to be fully human to minister to this Church, which too is human. That includes growing into mature emotional and psychological manhood-- and the Lord will use trials like this to form you as He wills.