Gwyneth Paltrow is that kind of person who likes to stay friendly with her exes.

Especially her ex Ben Affleck.

Friends tell FOX411 the star is big on sending personal notes and gifts for births and other major celebrations, and Ben and his wife Jennifer Garner have been on the lucky receiving end of such gifts.  

"Ben and Jen got one of Gwyneth's famous notes this year just after Seraphina was born," says the insider. "It was very nice, but it was a little too personal. Gwyneth made sure to mention how she was happy that Ben was finally creating the family he had always wanted, a family, which the two of them discussed in depth when they were dating. It just rubs Jen the wrong way."

But that's just the beginning of Paltrow's too-close-for-comfort behavior.

Gwyneth has enrolled her children, Apple and Moses, in the same Beverly Hills school that Violet Affleck attends, according to our source.

"Luckily, Gwyneth and Chris are barely in California three months out of the year, so Jen should not have to run into her too often at school," says the insider. "The other moms already have a problem with the paparazzi following the Garner-Afflecks, and Gwyneth Paltrow will only make the situation worse."

So far Garner, and Paltrow's husband, Coldplay singer Chris Martin, are playing it cool with the Ben/Gwyneth thing. Martin is so laid back, says our source, he actually promotes Gwyneth to stay in touch with Ben. And Jen is taking his cue.

"Jen will always allow Ben to have contact and friendship with Gwyneth," the pal says. "But she doesn't always like it."