Board Thread:General Discussion/@comment-31363379-20170221213509/@comment-86484-20170222011430

Undyne is female, and she loves Alphys. She seems to be a lesbian since she said the Garbage Dump is a great place to meet girls (and then said not to quote her on that).

Alphys is also female, and she's bisexual (or maybe pansexual). She's had crushes on many different characters, but since she started dating Undyne, she's only had eyes for her.

I think they make a really cute couple. ^.^