Most Helpful Guy
The best way of looking at it is this. If you can tell your SO what your doing, and who it's with, and they're OK with it, then it's not cheating by their standard.
If you feel guilty about it, or don't tell your SO because you don't think they'd like it, then you yourself know how they feel.
At the end of the day, each person has their own preference or limit when it comes to contact they don't like their having. If you want to do things they don't like, it's best to reconsider how much you like them and whether it's worth it.
Important thing to note. Getting a general consensus from a group of people on whether something counts as cheating or not is irrelevant. Because if you do something they don't like and they find out, saying "but it's not cheating" will not make them feel any better.