Completely fair on Matt! The relationship with him has the potential to get pretty complicated, in part because what Connor/the player might want from him isn't something he can give. In this case, sharing your firsts. It's possible Matt also wishes they could have had mutual discovery instead of how things actually went down...
As for the story, I'm not planning to lock anyone into a romance early on. If you want to focus in on just one guy, you can, or if you want to play the field, you can do that, too. About 2/3 of the way through the full game is when the first "defining the relationship" convos will start, but that doesn't mean every guy will want to keep things monogamous, if they even want to date... or that Connor has to stay faithful if he does enter a monogamous relationship. There will be some paths permanently closed off by that point of the game, but it won't be impossible to switch from pursuing one guy to someone else.