There is no specific reason strong enough for you being single. Your planetary positions in matters of finding a partner and settling down is not complex.
If you have been having pusruits which were more academic or creative in some way, that would have kept you alientaed from taking a strong decision on partner. You may have had a chance betwen Aug 2015 - Nov 2017, but all forces of will and planets may not have been aligned then.
Your next window of marriage or finding a partner is between July 2023 and June 2025.
If you for any unforseen circumstances, things don't work out for you in matters of finding a partner. Your bent of sould is towards spirituality and it may become difficult for you to find a suitable partner.
Mercury dasha during 20's and primarily focus on lagna and 10th house aspects. Moon being in 7th brings enemy at place and very fluid like approach, very watery approach like pisces in matters of relationship.
Ketu dasha and Rahu and Jupiter antardasha can bring partner possibility.