In personalitypages, the following is mentioned about ISTPs.
ISTPs take their commitments on a day-by-day basis. Even if they say "I do", it usually means "I do for now". They do not like to make lifelong commitments, although they may very well be involved in lifelong relationships which they have taken one day at a time.
So how is that some ISTPs end up married, and how long does it take for them to get there...years?