A senior male DF lives in a row of maisonettes above shops. The end of the walkway overlooks the garden of some other flats. When short of breath, he sometimes pauses and looks at the plants in that garden for a couple of minutes (certainly no longer and there are no other gardens nearby to look at). A woman resident there complained to DF's female friend that he stares into her window, making her uncomfortable. A couple of male residents allegedly support her.
Those windows have an extremely dark heat-reflective glass which you just can't see into from outside. You couldn't see if anybody was inside. DF doesn't know the complainant or which flat she's in. He just saw dark glass and didn't think about being seen from inside and ppl thinking he was peeping. He has no intention of looking into windows. His very highly valued female friend of several years (not GF) takes the woman's side (been friends with her for 1-2 months). She says he shouldn't even use those steps down to ground (there are others).
Has DF done wrong, and are either/both women being unreasonable? He doesn't like upsetting ppl.
YABU - He shouldn't look into the garden at all.
YANBU - He may be naive but hasn't done anything pervy or wrong. His friend should support him.