How to navigate the impracticality of Sigalovada sutra? Consider the advice of Buddha about friends and Wife in the Siglovada Sutta. 


  friends and colleagues so respected reciprocate with compassion in five ways: by protecting you when you are vulnerable, and likewise your wealth, being a refuge when you are afraid, not abandoning you in misfortunes, and honoring all your descendants.
  
  Some are drinking buddies,
  Some say, 'Dear friend! Dear friend!'.
  But whoever in hardship stands close by,
  That one truly is a friend.


Sleeping late, adultery,
Hostility, meaninglessness,
Harmful friends, utter stinginess:
These six things destroy a person....

In today's world where Smoking and drinking has become such a common thing and where socializing has become equivalent to having a few drinks at least a glass of wine, it's hard to find a guy to make a friend who would fit into Buddha's description of a friend here. I mean I have given up the vices but if I will try to find a mate like me its impossible, I will be left alone. 

A similar thing goes with the wife, 


  And, the wife so respected reciprocates with compassion in five ways: by being well-organized, being kindly disposed to the in-laws and household workers, being faithful, looking after the household goods, and being skillful and diligent in all duties.


In today's time of the hit and run relationships and all that we know of modern day relationships, this seems impractical. 

Following this Sutta will leave you lonely. How do you navigate this problem?
The truth of the Buddha's teaching is timeless and doesn't get affected by modern norms or customs. Imagine if it's influenced by social norms, then there'll be a possible scenario in a distant future where human virtures and values becoming severely degenerated. It'll be common practice and acceptable social norm for humans to do all kinds of evil and little to none of virtuous conducts. If going by the standard of that future time, the Buddha's teaching will be perceived as completely irrelevant, or at least only deemed valuable to a very very small number of people. The Dhamma drum will have so many pegs that it won't be able to make audible sound. So for the OP question, you'd have a better chance of finding a friend or a soulmate with similar mentality or conducts if s/he also cultivates similar virtues. Finding fellow Buddhist practitioners would be best, but any other sincere followers of other world religions would also be fine since they pretty much share similar codes of conduct. If all else fail, then it's perfectly ok to walk the path alone like a proud Rhinoceros