Let's restore the chronology of events and what they meant.
1. What choice do all three make in the library scene at the end of episode 4? 2 girls are staying as is in a couple, because they already decided it and MC stays only a friend to them, OR our MC joins them and they all together forms a 3-way relationship.
2. That particular conversation after hang out in EP5 end. Girls is concerned how serious MC is about them, because if it won't work out they may all lost each other. Maya grants MC free pass to explore his feelings and speaks about those "no strings attached".
3. We know that the girls in most of such games and this particular one is not dating anyone else and are not able to. So, obviously, under the "to all of us" meant that girls are also shouldn't be attached with strings to MC. Maya meant that it should happen naturally and with time. That was her main idea - no not force somebody (MC mostly) and let it happen naturally. And once again, ALL MGs in this game kinda like or love our MC (we know it). Josy at the beginning said - "let's take it slow", but she can't. Same happenes with Maya, she falls hard on MC, but she just blabber much less than Josy. So, J&M strings to MC are already strongly attached and at their maximum at the end of EP8. That's why the disaster happenes if MC picks someone else. The last word was for MC and his choice, they had already made their choice a long time ago.
4. In EP9 MC tells them that HIS strings are strongly formed and attached to them and asks them is it mutual and are they feel the same way for him (naive guy, lol). J&M are not accepting each other at that moment, because they don't have to accept and commit to each other, they are already a couple. It's MC, who is committing to both of them. And they are quite happy to hear it and it's a great relief, because all this time since EP4 they were kinda hanged.