I never understood the Sanz/Bobov minhag that married men do not wear tefillin but the bochurim/under-18s do.
If the minhag is based on the Zohar that one who wears tefillin on Chol HaMoed is Chayav Missah, then this must equally apply to all people. I can understand “bochurim not being oizek in chassidus”, and leaving lofty madreigos lifnim mishuras hadin until after marriage. But this isn’t a lofty height to achieve, this is a Halachah (al pi kabbalah) of CHIYUV MISAH.
I asked a very good friend of mine who has this minhag, and he just smiled condescendingly at me and shook his head.