Of course you can love more than one person at a time. Even romantically. I don't believe there is anything immoral about love - period. That's just non-sense. Love is precious not matter what. Being honest about it is where the morals are at. Of course most ppl don't want to share their lover. That's probably just biology at work - ya know something about fighting to get your genes out there first, yada, yada. Society also makes us feel shame or guilt and shakes it's annoying, crooked finger at loving more than one but who the hell cares about that lol (you maybe? idk). Another form of control for the masses.
lol... here's funny thing... a supposed quote:
"If you love two people at the same time, choose the second one, because if you really loved the first one you wouldn't have fallen for the second" - Johnny Depp It would appear that Mr. Depp does not believe in loving more than one at once and that he also views love as a mathematical logic problem in figuring out which one to eliminate from your equation. Ultimately how you want to live and LOVE is up to you - just be honest about it and you'll be happy.