In BDSM 'limits' are activities that people feel strongly about. Often strongly enough that they are prohibited. BDSM participants typically discuss and negotiate their limits with partners before any activity takes place. It’s essentially a more comprehensive consent conversation. There is a distinction made between hard and soft limits:
“Lesbian bed death” is the term used to describe the steep decline in sexual activity that is thought to occur in long-term lesbian relationships.
For the record, research has found that on average, lesbians do tend to have less frequent sex in long-term relationships than other couples (opposite sex and male same-sex relationships). However, a decline in frequency of sex occurs in pretty much all types of long-term relationships.
Additionally, it is also found that on average, women in same-sex relationships have LONGER durations of sexual activity (avg. 30-45 mins), compared to other types of couples (avg. 15-30 mins). And levels of sexual satisfaction in lesbian relationships are just as high on average as in opposite sex, and male same-sex relationships.
So they may fuck less, but when they do get down to it, they really put in the time and effort.