I think it's absolutely okay for you to get back together with him if that's what you really want to do, but I think it is completely unacceptable for you to flout the social distancing rules that have been put in place here to protect our precious National Health Service. These are:
"Everyone must stay at home to help stop the spread of coronavirus.
You should only leave the house for 1 of 4 reasons:
shopping for basic necessities, for example food and medicine, which must be as infrequent as possible
one form of exercise a day, for example a run, walk, or cycle – alone or with members of your household
any medical need, or to provide care or to help a vulnerable person
travelling to and from work, but only where this absolutely cannot be done from home
These 4 reasons are exceptions – even when doing these activities, you should be minimising time spent outside of the home and ensuring you are 2 metres apart from anyone outside of your household."
Coronavirus: Advice for everyone
Children whose parents have separated are allowed to be exchanged between those parents. Nowhere does the guidance state that one parent is allowed to spend time at the household of the other. In fact, the guidelines very clearly state that you must not visit anyone, not even family members with whom you do not live.
How does your boyfriend have the right to dictate to your IM what will happen with the children? How does he have the right to dictate that he will visit them at your house? And why is he seeing them every other day, when as far as I can remember, he didn't see them every other day under your existing agreement? I understand that he is probably at home full-time under our current rules, but that does not give him the right to spend every other day at your house.
If he is unwilling to have the children stay with him (and why was this? What does the virus have to do with having his children stay as they did before?), he should have asked via the IM for a different arrangement. You could have come to an agreement that he could face-time them on his days off, and pick them off and drop them back with you the same day only on his scheduled days with them. I think it's very obvious that you are glad not to lose the kids two days a week (perfectly understandable), but also glad to have him at your house every other day, showing his distress at being separated from you and heavily hinting that he wants to go back home. His behaviour shows that you haven't lost him, and that he's still heavily invested in you, the family and the home, and that's what you want. I can understand how you feel, and I think you should decide under what conditions you will get back together with him. That isn't a decision for anyone else to make for you.
What I can't abide is the way you are putting our NHS at risk. You might think that if he spends all his time in the garden, that this is social distancing under the rules, but it isn't, and under no circumstances can kissing him be within the rules, either.
It isn't for you to stretch and bend the social distancing rules to fit your private life. You can have as much contact with him as you want to, as long as you do it virtually until the current rules are changed. But for all our sakes, and the sakes of the front-line workers in the NHS, observe the social distancing rules and stop allowing him to set foot on your property.