Yeah, he did. They are officially lovers in that sense. I don't like the typical mc in harem too, being so indecisive and even worse is when it ends with no clear target. In my opinion, if you want to make a title with harem, then you should jolly well make it a real harem. If not, just stick to 1 person and make it normal romance lol. Well back in hs dxd, the other girls seems ok being in his harem, and rias doesn't really reject it either so I guess the end should be fine. You can try "mushoku tensei". It's also slightly harem, I guess? He married 3 girls already, and each of them gave birth to a child. In fact, one of them is pregnant again lol. They all living happily together in a house lol, this is what you can truly call a harem. Campione is also a nice harem title, the girls generally are fine with the mc having several wifes.