I would like to recommend a few gameplay changes:
-Add skill "service speed", it starts at level 1 and the girl will need 10 seconds to give the client the item he asked for automatically, being able to reduce to instant at level 10.
-Girls that aren't currently doing something will automatically go service a client if he is about to get mad.
In this game you kind of click a bit too much, I would think that an evolution towards a more automatized cafe and more event stuff happening would be optimal.
Related to the girls and relationships:
-It is nice to be lighthearted, still that doesn't mean that a bit of drama can't be added, like if your girlfriend catches you doing stuff with a girl she may be mad at you, even possibly to break up and have a different girl as the official girlfriend. It can be quite light doing stuff like that.
-On another point it would be nice that you could actually convince the girl to let you have sex with others or even make her into a cuckquean (I feel this stuff is so underused when it fits harem settings so much).
-Related to NTR... I feel it's okay if we just avoid drama on this aspect, girls can cheat and fall in love that's not an issue if you gave them the pin, if you just avoid the pathetic MC then that's perfectly fine.
-On another point I would kind of hope that girls could become submissive or dominant towards the MC and with related effects for it, for example a dominant girl will make you give her more money or even be the one that teases you and is on top on sex scenes while submissive ones obey all your orders without issue for example.
To be fair I just would like to be able to break up, have a different official girlfriend and stuff like that. Overall it's a nice game, but I feel it still needs a lot of work on relationships.