This was one of the reasons I started using cheats on console. I add the Beloved trait to all of my Sims at the point of creation using the cheat traits.equip_trait trait_Legendary (with testingcheats true entered first which disables console achievements).
My Sims are mostly from families that are spread out through different worlds and I find that even regular phonecalls don't help maintain relationships. Plus Lovestruck adds romantic relationship decline too. So for me it's one of the most important traits in my game. They don't even start out with high enough relationships bars when created together in CAS. So I decided it was worth disabling console achievements for my current save files to stop relationship decay.
