My own opinion is that "seeing other people" has no place in M and would not be permitted during sabbatical either. For me, personally, that would be a deal breaker. I know that some couples try the "open marriage" route, but I don't know how often those Ms turn out to be healthy and successful. Even if D, the "expert" recommendation is to allow yourself 1 year on your own for every 4-5 years of M before you get involved with someone else.
me: 47 H: 48 he has 2 grown sons M 1995(my 1st, his 3rd) hit iceberg 6/07 S 9/26/07 before now