Time is a difficult one. Most people work sort of Mon-Fri 8-6, pretty much leaving weekends as their only free time. Especially if you have things to attend to as well. I've had to consider previously that I would have to cut the time I spend with one partner (which was only on weekends) if I wanted to see this new guy (who I could also only see on weekends) and he understood that because he knew the same might be true for him when he met someone down the line.
Luckily, my current partner works from home and is self employed so he sets his own hours. We do spend lots of time together on weekends but that isn't the only time we can spend together. We would see each other slightly less if/when either of us find a new partner, but we are prepared for that and know we will have to adapt accordingly.