Ok so, here's some hc for a Mr Rosa x Marty scenario
• They first meet a parents-teacher conference. Marty has heard a lot about Mr Rosa from Nate, so he was looking forward to meet Nate's favorite teacher.
• They had a pleasant first meeting. Mr Rosa talked about Nate's creation in art, and Marty is glad that there is one teacher in the school that Nate genuinely like. After talking to him Marty can clearly see why.
• They exchange phone numbers.
• Some time later, Marty had a blind date that did not go well. Feeling kind of depressed about his non-existant love life, he wanted to talk to someone. Mr Rosa came to mind.
• Marty called Rosa and they decided to meet up again during the weekends.
• They meet up at a cafe, and started chatting about their days. About Mr Rosa's art class and his students, Marty talking about his disastrous blind date and his kids' shenanigans. For some reason, the last date didn't feel so bad when he laughed about it with Rosa. (who insist on Marty calling him Ken.)
• They hang out a lot more after this, and Nate and Ellen started to notice, particularly Nate.
• He started asking his dad and Mr Rosa about their relationship. Marty insists its nothing, just a couple of friends hanging out. Mr Rosa said the same thing, but Nate is sure there's something going on.
• Sometime later, Ken asked Marty out for dinner. Just as friends, but for some reason Marty feels nervous.
• As he was dressing up for the dinner date (no, its not a date-) Nate finally speak his mind.
• "Are you two going out?" "What? No, of course not!" "You're having dinner together" "As friends" "And you're dressing up in a fancy suit" "What's wrong with that?" "You only wear suits on dates" "No, its just dinner with a fri-" "Dad, this is totally a date"
• Nate said he doesn't mind if he and Mr Rosa are going out, and it'd be cool to have Mr Rosa as a stepdad. At that point Marty just left, feeling embarrassed.
• At the diner, Marty keeps thinking about what Nate said. Somehow, the though of being in a relationship with Ken doesn't so bad. He likes the guy, they got along well. Much better than he ever did with any women. But he doesn't like men like *that*. (At least, he doesn't think he does. or does he?)
• After the dinner was done, Marty offered to drive Ken back home. During the drive, Marty hesitantly asked Ken if he wanted to start dating.
• To his surprise, Ken said yes.
• They went out for a couple of months. Marty felt a lot happier than he ever did, even more than he did with his ex-wife. Ken also confessed that he never though he'd ever find someone who he could be in a relationship with.
• Marty proposed some time later and Ken said yes. They have their wedding during the summer. Nate was the ring bearer.
• After the wedding Ken moved in with the Wright family, and ever since then he became Mr Ken Rosa-Wright and raise two kids alongside his new husband.