This is a perfectly acceptable British style Rom-Com. Think Love Actually, or Notting Hill, or basically anything with Hugh Grant.
Now, to be fair, it feels like very much a first effort from everyone involved. There are inconsistencies, occasional weird pacing, changes of tone, fragments of story line that go nowhere. But those are all minor; the effort as a whole is kinda charming and cute, and you land up wishing the best for everyone involved.
Don't be put off by the first five minutes (which aren't bad so much as slightly confusing and disconnected), give it about fifteen minutes to suck you in, and you'll want to watch the rest of it!
A better description of the storyline would be that two very attractive women, both dating the same guy (and aware of each other) have him drop out of their lives, so they hire a female PI to find out why he dumped them and (obviously!) she also sees something in him. But why he did dump the two supermodels? Is he going to get back together with one or both of them? What makes him so compelling?