Dear Dorrie, 

I would agree with what your conscience seems to be telling you. You are not being fair to your friend, since he is expecting much more from this relationship than you are prepared to give. He is open to it leading further, and you know that you shouldn't let that happen since you believe you have a vocation. 

So this is the situation you are in: you are trying to do something good (be faithful to your possible vocation) but to do that and date at the same time is leading you to be unfair with your boyfriend. So your dating has taught you an important lesson, that dating and vocation are now becoming incompatible, you can't honestly do both at the same time,  one or the other is going to be compromised. Now may be the time to take another step in your vocation journey (I am not calling it discernment since you seem to have discerned that you may have a vocation), the step of putting your vocation first and recognizing that even though dating feels good it is not the wisest thing for you at this stage, or the fastest thing for your friend. 

Speak to Christ about this when you go to Communion. 

God bless.