Like everyone else, I'm feeling sorry for Stand and he's already the "nicer" 2nd ML. He's also STILL in love with our girl (plus points for me, guy is still loyal despite getting a public rejection).
This is tough. Del isn't the type of abusive ML like CEO charas, he's also not a pushover meanwhile from what we can briefly see with Stand, he's the nicer, more stable (I'm a bit confused with the rings part, was he being robbed and went full self defense?) 2nd ML but could be a pushover.
Del right now NEEDS our girl (and no other woman is gonna be capable enough to stay with him. Sure a select few may actually not be aware of his identity and like Rinrin could get blinded by his sex appeal but once they see his other job, most women would faint or end up getting scared sh*tless) and other than scamming her with the marriage, he does treat her right. Stand has potential to be a great husband chara (kind + outstanding job + loyal to Rinrin despite the public rejection + as a bonus, mildly dismissing her past memories comment) but a shame our main couple is meant to be already, he certainly can find another one.