It has been alluded to before but it is not only prescribed medicines that can affect both our bodies and our libido. Those of us who've been dealing with elevated estrogen in our hormone stew, often since we were teens, have lived with softer bodies with curves. Then we add the changes that come naturally with aging. That includes diminishing testosterone which seems to liberate the estrogen always present. In addition to breast growth, I've experienced a marked drop in libido and shrinking of my penis. We understand in comparing male and female anatomy that the male penis is equivalent to the female clitoris which those of us with experience in such things know is much smaller than a male penis. Is that all the function of the level of testosterone present in the body? No doubt it is more complicated than that, but there is no doubt a smaller penis has arrived at the same time my breasts have grown. And libido definitely disappeared with the testosterone. Erections are few and far between. Since I live alone my situation doesn't impact a partner but I have to say, the pleasure I take in the presence of breasts filling the black brassiere I'm wearing at the moment is not quite so easily expressed as it would have been when I was younger. This, of course, is simply one more opportunity to practice acceptance.
I read a conversation on a crossdressing website I occasionally visit about sexual activity. The vast majority of men who love putting on women's clothes are very seldom sexual with their partners, and not simply because their partners are distressed by their gender-bending behaviors. Of course, these men are likely not dealing with gynecomastia and its related hormonal shifts... but it is a simple statement of fact. I recall the old adage...
If you put a jelly bean in a jar each time you have intercourse with your wife in the first year of marriage... and then remove one each time you have intercourse after the first year... it is doubtful you'll ever empty the jar...