Having "a life" does have to be going out with groups of people. It is all about what you enjoy.
Some people enjoy the large social setting of an 80's party or shopping. For others the same enjoyment can be found spending just with their SO hiking or biking. It depends on if you and your partner are introverts, extroverts, or one of each (which can be a challenge).
I've been with my husband 11 years (and married 7).
We met through running, but run seperately. To both of us, that is our alone time, where we recharge. We both run decent volume (70+ week), and even run with other people.
The key is setting time aside for just us. It took us a while to realize we needed to do that. So we set a couple of nights a week aside to do something together. It might be going to a play or concert, a group party, or a hike with the dog. Doesn't really matter as long as we are spending time together. We don't have kids, but are very busy with coaching, running, and our day jobs. Our Coaching and day jobs can take up as much as 60+ hr a week.
Running isn't going to tear a healthy relationship apart, but it will likely to the last straw in an already weak one. In that case so will a weekend out with the boys fishing, or a shopping trip, or your favorite TV show, or the grass not being cut,etc.