Ok, so, I admit that just reading that title gave me flashbacks to some serious garbage doujins. In fact, it seems like a really shitty trend in JP right now where the dad cucks the son and the ex gf/lover/this set up becomes his "mom". Ugh, anyway, that title plus the characters themselves set off some serious warning bells.
I'll give it about 10 chapters before I decide, but as
@swain123 pointed out, there is another one like this. This obviously isn't bad so far, just seems a little too "forced" for my taste.