Daas Yochid, both husband and wife have to want the Kollel lifestyle, like they want air to breathe, and be totally focused on Ruchnius, except for necessities, otherwise it spells misery for all involved.
Putting on my protective gear- here I go:
These days living in Lakewood , the biggest Kollel community in the US, often means keeping up with the Joneses. Lakewood is no longer a community restricted to Kollel familes, with Kollel style homes, cars and clothing, or even food, of old. If either husband or wife will feel unhappy if they cant have what those around them have, Kollel isnt for them. It will cause major unhappiness. On the other hand, if they are TOTALLY ibergegeben to learning, and are ok getting things from Gmachs, etc, and couldnt care less if the Gashmiusdik crowd considers them nebby, they will not even notice/care what others have, because they’ll feel “Toirah iz de besta Schoireh”.
There are many Kollel yungeleit like that, where the “real” Gedolim come from, but too many who choose the Kollel lifestyle are not on that Madrega these days, and end up being disenchanted.
Generally, those who are OK living in smaller, less Gashmiusdik communities, have an easier time with the Kollel lifestyle, long term.