[masaegu]

Originally Posted by StonerPenguin

To go back to the dialogue I wrote before;
「そっか　来栖君なんかその年でもうパパだから大先輩 だよねぇ」
"I see... since you're already a father at such a young age you're more experienced"
[I hate to TL 先輩 as 'more experienced' but 'senior' doesn't work here... Also, I'm like 80% sure that Sakaguchi (the girl) is older than Kurusu since he's a teenage father]

Right. Someone doesn't have to be older. If he is more experienced than you in a certain area, he is a 先輩.

「あー　私の彼氏も来栖君みたいな奥さん一途で優しい人が良かったなー」
"Oh, I wish my boyfriend was a faithful and kind person like you"
[I kinda feel like a conditional like ～と or ～たら has been omitted here but maybe I'm not looking at it right.]

Nothing is omitted. The も and が serve sufficiently as conditional. The が here is almost equal to なら、だったら, etc. in meaning.

「それじゃ今日で一応　お世話になりましたって　こと で」
"Well then, I'm grateful for your help today"
[I don't think that's the best translation possible considering they're parting ways. Hmm, I may just need to ponder on it some though]

It's actually impossible to translate this. There is so much being said with a few words.

You seemed surprised that I knew she was leaving the guy, but a native speaker would only have to read the それじゃ今日で part to know that something unusual is happening. You don't ever say 今日で in discussing events happening today, do you? That's the power of particles. They carry so much information.

一応 was another hint. The reader would know that today is being some kind of a turning point.

たってこと で was yet another and the last blow. You can be sure that something is ending.

Your TL "your help today" is incorrect. It's the help that she has received during the months/years she has been with him.

I've seen 「子供が出来た」 several times in this manga and I just assumed it meant something along the lines of 'having a kid' or getting pregnant. But does it specifically mean 'got pregnant'? I may need to go back and check my work now ;p

It almost always means "someone got pregnant". You haven't given birth to it.