Money Moral Dilemma: Should we stop splitting the bill?

Ia agree that it does look as though the OP's friends are either taking advantage of them or very thick-skinned & thoughless.

However, as there is an established pattern of splitting the bill I think it would be wrong for the OP to wait to the end of the meal, when the bill comes, before saying they will only pay their own.

I would suggest that when they are seated they ask the waiter to keep the bills separate (Asking at the outset is much easier for the restuarant; asking for separate bills at the end will make the wait staff hate you!)

This means your 'friends' know at the outset that you are each paying your own (so they can chose to order less if they want)

If they comment on it you can (depending on what you feel comformtable saying) either say that you are havingto budget but don't want to cramp their style or, if you know them well and think they are simply thoughtles rather than deliberately ripping you off, say that you sometimes feel irritated that they chose more expensive stuff but don't pay extra, and that by having separate bills eveyone can order what they want and enjoy themselves without feeling resentful, or guilty.

I think that it's always sensible to say something at the start of the meal - easecially in large group or if you don't know the other people well. If I eat out, I would normally expect to split the bill equally if I'm with people I know well, and to pay for what I've had otherwise, but in circumstances where I think I'm likelyto spend significantly more or less that the others I will say something at the start so it's clear I expect to pay only for what I order.

I admit that the person who pays on the credit card and takes the cash is a tricky one - I will often saysomething like - 'oh, some of that cash is for the tip - wouldn't it be better to leave that as cash to be sure it goes to the waiter?'
That way, it doesn't offend the card holder as you're not accusing them of pocketing it, as you've framed it on the assumption they'd have put the tip on their card as well, and it is hard for them to object without then looking as though they are objecting to tipping!

(If I'm the one with the card, I will count the money and leave the tip, including my share of it, as cash)