Perimenopausal changes aren't exactly the same for everyone, but if you start noticing changes in your arousal, orgasm, sleep, energy, or mood in your late 30s onward, perimenopause might be at least partly responsible. Your doctor can look at hormone levels for a clue, but our hormone levels aren't all the same either! Read up on this topic and see how much reflects your experiences—Heather Corinna's book What Fresh Hell is This? is an excellent place to start. And if you start experiencing hot flashes—that's a ​definite clue. 

The easiest way is to stay connected to pleasure for the whole menopausal transition. The ways you like to be sexual may change, or they might stay steady, especially if you decide to do hormone replacement therapy. But the very best reason to continue sexual pleasure (via play with a partner, or solo) is to keep your body accustomed to those wonderful feelings. And it's also extremely helpful as you keep track of what does change. If you have a partner, make sure to let them know. 

Not really, though some find their lube preferences are not pronounced or that they don't change much. But you might definitely find some lubes are irritating that were not in the past—as vaginal tissue gets more sensitive, it might not appreciate some ingredients! If a lube irritates you: Don't use it. Try ​something from Good Clean Love or another company that makes lubes with post-menopausal folks in mind.

Vaginal penetration may be painful especially for those who don't take HRT or who stop having sex for an extended period of time during the menopausal transition (sometimes those who have been divorced or widowed step away from intercourse and notice the difference if they then find a new partner). You can try topical HRT cream (by prescription), which can add vaginal resilience. Make sure you are using a lubricant that feels great to you. Don't rush it! In particular, make sure you are fully aroused before any vaginal penetration. Dilators might help with this issue too. Above all remember that intercourse/penetration are NOT the only kinds of sex! Oral, hand jobs, toy play, BDSM, and even anal may be easy to enjoy for many, and it's important to be attuned to what your body and mind do enjoy as you explore after a time of change like the menopausal transition.