Abundant Loved Gifts by source - per week counts (2 gifts per week assumed). Late game expected, prioritizes crops, forage, gems, then cooking.
Loved gift is +80 points, 250pts/heart (3.125 gifts/heart)
Loved gift on birthday is 640pts (2.5 hearts)
Once maxed, hearts no longer decay
Talking is +20 (daily) when not in a special animation
0 to 8 Hearts (marriage candidate) is 20 non-birthday loved gifts if you only talk to them on gift days (10 weeks)
0 to 10 Hearts (marriage candidate) is 25 non-birthday loved gifts if you only talk to them on gift days (12.5 weeks)
A single birthday gifts saves around 8 gifts, very worth it.
Non-active romance characters decay at 2pts/day, over 12.5 weeks that's 125pts, or 2 more gifts. If you just talk, that's an additional 100pts/week, saving an whole gift.