At lunch with lady friends, we shared a sampler. One of the ladies would talk and bits of food would land on our communal dish.
I found this repulsive but didn’t want to say anything.
Would it be good manners to take some of all of the items and put them on your own plate?

- Delicate Matter

Avoid the flying bits rather than worry about delicacy; it’s a matter of hygiene, certainly not your manners.
Yes, it’s acceptable AND self-protective from potential germs, to take a share of a sampler plate onto your own.
Even without airborne debris, there’s cross-contamination when several people dip their used forks into a common food source.
No need to embarrass this one person, but more will be grateful when you introduce the new sharing style.

I’m 20, and met a guy online (26) who lives in another country.
After five months, he came here to see me; he has many relatives here, and we’ve been seeing each other everyday. We’re so in love, but my mom keeps saying I should look for someone else, because he’s returning to his country and we won’t be able to see each other for some time.
I can see my future with him, but I easily get persuaded by what others say.
I don’t stop to think about what I want.
What to do?

- Stuck and Need Help

Rather than add another opinion to confuse you, let me point you to a different consideration: If what you think isn’t firm enough to withstand others’ opinions, you’re not ready for a lifetime commitment.
Enjoy his company; value what you’re learning about him, and about being in a relationship while he’s there. When he’s leaving, acknowledge that a protracted long-distance attachment is too much when you’re still young and indecisive.
Both of you need to freely date others when you’re apart, and let time, more experience and the maturing process help you decide - when it’s possible to get together more often – whether this can last.

I’ve recently become engaged, we couldn’t be more excited about planning our wedding… until his mother got involved. While she’s trying to be helpful, her “advice” always feels negative – what we shouldn’t do, what we shouldn’t have, etc. It’s straining and upsetting both of us.
Rather than asking what we want, she makes assumptions, suggests only what she thinks, constantly comparing us to couples whose situations are nothing like ours.
I’m reluctant to say anything because I think she’s a wonderful person and I don’t want to damage our relationship. Her comments are usually directed at me, when my fiancé isn’t around, so it’s hard for him to say anything to her, either.
We’ve started to avoid spending time with his family to not deal with her negativity or pushy suggestions.
How can we politely tell her to butt out without hurting her feelings?

- Bombarded

“Butt out” is never polite and not necessary… yet.
Instead, figure out your own wedding plans together with your fiancé, and leave some questions about the things for which you need more research or thought. Ask his mother to help you with those areas; or simply assign her some you don’t feel strongly about, e.g. perhaps she’d like to address the invitations, or choose options for the table centrepieces, whatever.
She does have some experience that may be useful, so let her have a role… as the groom’s mother she may feel that “advice” is her only involvement in what, for her, is also a big day in the life of her son and family.

I’d walked with a lady for four years, and treasured her friendship. Her life changed for a while, but I told her that whenever she could walk, to call me.
Lately, I see that she has a friend come over and walk the same time as I’m out.
I get a little angry as she knows I miss her. They also walk the same way I go.
Why would she deliberately be doing this?

- Walking Alone

She’s likely not deliberate, just not thinking along the same lines as you. For her, it’s more about the exercise, but when a (closer?) friend came along, she agreed they’d walk together.
Try to not get emotionally agitated by this, it reduces the physical benefits.
If need be, walk at a separate time, and/or in another direction.