I would like to add, I certainly believe that we can truly love God, despite being unable to ever fully understand His nature. I would argue that we have no issue loving our best friend, our spouse, our parents, etc. despite not knowing everything there is to know about them.
I agree with others in that we can conceptualize God, with limitations. We can understand aspects of His nature and things that He has revealed, especially through the Incarnation. Love, as others have said, is not about feeling. Love is not a feeling, especially when one is talking about the Church. Love is the direction of one’s will. Direction for the other person is love, against them is something else, be it apathy or hate or what have you. God loves us. He wills our good, and is the source of the love shown to us by those around us. Through my parents’ love for me, God’s love for me is evident. I strive to be that same source of love for those around me, particularly those who do not know God. I understand aspects of God’s nature through those who love me, and like those people in my life, He desires that we love Him in return. My parents would be very hurt if, after providing so much time and affection and money and company and so on for me, I ungratefully ignored them, never called, never visited, refused to hug them, and overall just didn’t share aspects of my life with them in return for their doing the same for me.
Likewise, God wants us to do the same with Him. To share our troubles and joys and flaws and accomplishments, to talk to Him. I do not go to mass every Sunday (and sometimes confession every Saturday) out of duty, or at least entirely out of duty. My motivations are to show to God what limited reciprocation I can of His love for me.
All that said, I think one of the unending joys of Heaven is that, no matter how long we are there, how long we are in God’s presence, we will never reach a point where we fully understand Him, and particularly will never reach a point where we fully grasp the depth of His love for us. Even in eternity, we will not be able to reach a point where God’s love does not overwhelm us. Knowing how much our parents love us is already basically incomprehensible.