Lama Ole’s answer:
If the existing relationship is going well, if both partners enjoy each other’s company and are doing well, then I would certainly look for another lady or gentleman. Even if there are obvious signs that things aren’t working anymore, I would wait until the karmic connection between the partners has dissolved.
If two people come together too soon, while the former partner is completely unhappy about the separation, then the new couple is creating negative karma. One should wait for the relationship to fall apart by itself. And then, when it is over and the old partners are able to wish each other well, the new connection will be good too.
When we have a sudden feeling of attraction for someone, it is because we have a bond with the person who has crossed our path. And it is not possible to make any moral judgement about it. I would never judge this. Nevertheless, it is advisable not to follow this feeling immediately; it might be strong, but it also might pass by again quickly.
One reason to take your time when going into a new relationship is that both good actions and bad actions in the past can be the cause for people to come together. Within a short period of time, one can feel whether something positive or negative is approaching. In a situation where things become more and more difficult, that which ties you to the other person is something bad, and you still have the chance to move apart again. This is why you shouldn’t throw away what you already have too quickly, just to get into something you are not sure about. That’s my advice. Be a bit mindful—both good actions and bad actions have their glue and bind us together.
Sometimes a partnership might have simply become a bit boring. In that case, the relationship may actually be strengthened and revived again by having a new player join the game for a short while. That advice is important for laypeople. But keep in mind that the purpose is to preserve the relationship, in particular if there are children.
For yogis, something else is important. Here the point is to use one’s sexuality to create the maximum amount of joy—so as to develop as quickly as possible. For the yogis, it is crucial to get to know people to practice with, and to experience a great amount of space and bliss. And here, one isn’t necessarily limited to one person. One can let oneself be inspired by a few partners.