I get that this is here to introduce something like a phase 2 or second arc of the plot about washio, but I think that we're given too little to deduce too much from, since everything is sprinkle sprinkle and we just gotta know whats going on
let me guess, dragon girl is doing all this because we're gonna see a flashback of something related to the monster girls hurting washio and dragon girl does all this to save him. save him from the suffering of monster girls/hybrids
I think Washio is also under mind control/brainwashed by the villain guy or hes doing this as another self-sabotage so the Monster Girls can move on from him as he's not "worthy of their love" or something. Leaning more towards the latter.
I'm hoping it's an illusion, or brainwashing, or a trick on MC's part, or something like that.
If he genuinely said that awful shit just because he was depressed, then that would put MC way below the point where I can ever find him likeable again.
this author wrote themselves into a corner, so without some deus ex machina ass pull this won't be resolved. this "drama" actively makes this manga less interesting and enjoyable to read.