Well...their relationship obviously ex-roommates. Phoebe can't stand living with Monica, so she moved to her grandmother's house.

Season 1

Monica: Hi.
Phoebe: Hi.
Monica: What are you doing here?
Phoebe: Nothing, I just thought I'd stop by.. y'know, after the uh... that I.. y'know, so what are you doing here?
Monica: I'm not really here. Just thought I'd drop these off...on the way.. my way... Do you come here a lot? Without me?
Phoebe: No. [Monica brushes Coma Guy's hair in the other direction] No! No! ...So, um, do you think he's doing any
better than he was this morning?
Monica: How would I know? I-I wasn't here.
Phoebe: Really? Not even to, um, change his PAJAMAS?! [Whips back the sheet]
Ep. 11 ~TOW Mrs. Bing~

Season 3

Monica: Pheebs?
Phoebe: Huh?
Monica: Where’s your bed?
Phoebe: It’s not in the apartment? (Monica gives a ‘Come on’ look) Oh no. I can’t believe this is happening again.
Monica: What?
Phoebe: Okay, enough with the third degree! I-I’ve, I don’t live here anymore.
Monica: What are you talking about?
Phoebe: I’m sorry, I-I-I-I don’t live here anymore. I-I didn’t know how to tell you, but y'know everybody else knows!
Monica: Everybody knows!
Phoebe: That was supposed to be a good thing, I forget why. Just listen, Monica, I, do you know, okay, do you know, I couldn’t sleep for like a month because I got like a dot of ink on one of the sofa cushions.
Monica: Well, you-you coulda just turned the cushion over.
Phoebe: Yeah, I would’ve except I had a big spaghetti stain on the other side.
Monica: What?!?!
Phoebe: Okay, this is what I’m talking about, this. I-I need to live in a land where people can spill.
Monica: You can spill. In the sink.
Phoebe: Aw, honey it’s not your fault, y'know this is who you are, and I love you, and I want us to be friends, and if I keep living here I don’t see that happening.
Monica: I love you, too.
Phoebe: Aww, good. (they hug) What?
Monica: What? I’m just said.
Phoebe: No you’re not, you’re wondering which cushion it is.
Ep. 6 ~The One With The Flashback~

Season 4

Phoebe: Okay, is this the day of good news or what? I got us a job! The wedding reception.
Monica: Ohh! Umm, Phoebe, I kinda need to talk to you about that. (Rachel excuses herself) Umm, well I-I-I think it might be time for me to take a step back from catering.
Phoebe: But we’ve only had one job.
Monica: I know, but now we have this second one and it just, it feels like it’s snowballing, y’know?
Phoebe: Yeah! What are you saying?
Monica: I got offered the head chef job at Allesandro’s.
Phoebe: What?
Monica: It’s okay, ‘cause y'know what? You don’t really need me for the business.
Phoebe: You’re the cook! With out you it’s just me driving up to people’s houses with empty trays and asking for money!
Monica: All right. But umm, I-I-I’ll pay you back all the money you invested, and you can keep the van.
Phoebe: For what? I can’t believe this! I gotta get out of here. (leaves)
Monica: Phoebe, wait a minute! (runs after her, leaving Rachel alone)
Ep. 9 ~The One Where They're Gonna PARTY!~

Monica: (entering) Ohh, here you are. Y’know, I’m-I’m glad you decided to hear me out.
Phoebe: Okay, I’m hearing.
Monica: I’ve been doing a lot of thinking. A lot! And umm, well, I came up with a whole bunch of businesses you can do with your van. Okay umm, you could be flower delivery person.
Phoebe: What?!
Monica: Or! A bakery delivery person.
Phoebe: I wa-I wa-I wa…
Monica: Pizza?!
Phoebe: Monica!
Monica: All right, I’ve got a whole bunch of uh-uh, stuff in this area, but umm, I’m getting the feeling that you don’t want to deliver.
Phoebe: No.
Monica: Okay. I’m guessing that if you don’t want to deliver, you probably don’t want to pick stuff up either.
Phoebe: No.
Monica: Y’know what, let’s do the catering business.
Phoebe: Really?! Are you sure?
Monica: Yeah, y'know I-I made a commitment to you. Y’know what, it’d be, it’d be fun.
Phoebe: Oh! It will be fun! Ohh! Yay! Oh! Okay, ooh, let’s plan the wedding reception. (She grabs the notebook which
Monica used for her ideas and starts flipping page after page after page after page after page to find a blank one.) Wow! You really wanted me to do something with this van. (pause) Y’know what, I want you to take the chef job.
Monica: Really?!
Phoebe: Yeah. That’s what you really want. Yeah, I don’t want to be the reason you’re unhappy, that would just make me unhappy, and I really don’t want to be the reason I’m unhappy.
Monica: Thank you.
Phoebe: Besides, it might be kinda fun to form the new A-Team.
Ep. 9 ~The One Where They're Gonna PARTY!~

Season 5

Phoebe: Mon, can I talk to you for a sec?
Monica: Yeah, what is it?
Phoebe: Umm, I lost one of your earrings. I'm sorry! I am so, so sorry!
Monica: (shocked) Wow! All right well, I mean, what can you do? If you lost it you lost it.
Phoebe: I will replace it, I promise. I feel so terrible.
Monica: All right, sweetie that's fine. You didn't do it on purpose.
Phoebe: No.
Monica: Look at you! Come here! (They hug.) Feel better?
Phoebe: Yeah! You're the best!
Ep. 19 ~The One Where Ross Can't Flirt~ and thanks to Anna