Do you have a family? A family, an SO or kids is the best way to understand life through other perspectives.
Have kids because you want them. Not because you think they'll give your life purpose.
Starting or growing a family is a terrible way to solve problems.
If interaction with kids seems like a good use of time, start by volunteering with mentoring organizations like Big Brother/Big Sister or Boys and Girls Clubs. Or help out with the kids programs at church/temple/synagogue if you're into organized religion.
If that pans out well, consider babysitting for foster families. Foster parents do incredible amounts of good for society and get run into the ground in the process. It seems simple, but giving them a night off here and there is a huge help.
If that goes well, then maybe consider adopting or starting a family. At any rate, there are a lot of young people out there that could use positive (especially male!) role models.
Also, the term "significant other" can mean more than spouse (which implies marriage): [boy|girl]friend, life partner, close-friend-kind-of-person, etc.