Tony Stark to Captain America: “And the one thing that we have never, ever forgotten……is that we couldn’t have done it without you.” || Captain America: Man Out of Time (2010) #3
A couple months ago I answered an ask from someone who had a very similar question (more or less, what are the times in canon when Steve and Tony were getting along?), except they additionally wanted no secret identity, so that rules out early canon. What you’re left with in 616 at that point is basically Avengers vol 3, the beginning of New Avengers vol 1, the second half of Avengers vol 4, and actually they’re friends in the current (vol 8) run but they haven’t really shared page time much lately.
But if you want Steve and Tony being honest-to-God cute, mostly what you want is either Not Technically 616 or found only in miniseries or annuals:
Avengers: Back to Basics. I’m pretty sure I recced this recently, but I might as well rec it again. It’s a six-issue mini that is a tour through some of the team’s earlier years, and it’s not exactly canon, but Steve and Tony are friends, it’s very cute, and at one point the villain makes Steve wear his old Nomad outfit, so obviously it’s worth it for that. It’s not out in trade yet, but it will be soon. You better believe I’m buying a copy.
Captain America: Man Out of Time. I will always rec this miniseries, solely because it features Tony taking Steve on a date at the Smithsonian and showing him the wonders of the future. Including Radiohead.
Avengers Prime. Basically it’s about Steve and Tony learning to love each other again after Civil War. There are rescues, shared horseback riding, gratuitous nudity, and hugs.
Avengers Annual 2013. This is the annual that was released during Hickman’s Avengers run but it has nothing whatsoever to do with it; it’s a Christmas issue by Kathryn Immonen. If you’ve seen the panels where Tony makes Steve refer to himself as Captain Handsome in order to access the Avengers’ systems, that would be from this issue.
One Night in Madripoor (Captain America & Iron Man #633-635). A three-issue arc of Captain America from 2012 in which Steve and Tony team up in Madripoor and fight AIM and MODOK and robot bees together. There is a lot of banter and it is adorable.
Marvel Adventures: Avengers. This is not 616; it is its own universe. Marvel Adventures was a line of all-ages comics. MA:A ran for 39 issues, but if you want everyone being happy, this is what you want to read; yes, technically, it’s for children but I assure you that it is an awful lot of fun for adults. The two issues Steve/Tony fans like best are #27, in which Steve and Tony basically go on a basketball-playing date, and #30, in which they basically go on a date in the park. They’re VERY CUTE. Definitely BFFs. The rest of MA:A is great too. So fluffy!