My now-husband and I mostly courted over the phone and we never ran out of things to talk about, “shallow” and “deep.” Once we “got serious,” we talked each night for over an hour, usually. Plus, we e-mailed a few times a day as our work schedules permitted. It was hard to be apart.
If one does find that s/he is running out of things to say, I suppose it could mean one of two very different things: 1) you don’t share enough to seriously consider marriage to the other person and should consider moving on, or 2) you’re so much on the same wavelength that you need to start seriously talking marriage with the other person so that you can make a life together and never cease having things to talk about!
Peter and I met on Ave Maria Singles in the Fall of '03, were engaged by Christmas of '03, were married in the Summer of '04, and had our first baby in the Summer of '05. We’re now pregnant with our fourth, so we have no shortage of life experiences to talk about and enjoy together!
God is not going to hide His perfect will from those who sincerely seek it, so if a couple is praying and using their God-given gifts of discernment, they can have peace that what they are discerning is God’s will for them and that He will make a way.
I hope this helps. May God bless you!